Movies are big business - one of the biggest - and the amount that they're grossing on average is generally going up by the year, even adjusted for inflation. As things stand, the highest-grossing movie of all time is 2009's science fiction epic Avatar, which has pulled in $2.788 billion worldwide.
As a general rule, the cream tends to rise to the top and the majority of those movies that are in and around the top 100 of all time when it comes to box office gross - those that earn in excess of $500 million - are good films for one reason or another, whether they're brilliantly written, visually stunning or just downright entertaining.
That's not always the case, however. Some films that simply aren't very good manage to trick audiences out of hundreds of millions of their hard-earned dollars - if not more than a billion - through things like great marketing, a decent predecessor/being part of a popular existing franchise or overly high expectations.
The following are ten unequivocally awful movies that have performed remarkably, bafflingly well at the box office.
10 Cars 2 ($559.9 million)
Cars 2 was the 2011 sequel to the popular 2006 Disney Pixar movie Cars. The movie, about a bunch of anthropomorphised vehicles, out-grossed its predecessor by almost $100 million. Yet, it simply wasn't as good.
In fact, Cars 2 received a worse reception than any other Pixar movie, period. It's the only Pixar production to have garnered a "rotten" certification on the tomatometer, rated at 39%. Critics deemed it to be a poorly written and poorly told story, with too much crammed in.
Having cost $200 million to make, it made back nearly double its budget with $559.9 million in takings, in spite of the fact that almost everyone agreed it was garbage.
9 The Smurfs ($563.7 million)
With a stellar cast and voice cast that included the likes of Neil Patrick Harris, Hank Azaria, Katy Perry and Alan Cumming, 2011's Smurfs movie had all the ingredients to be at least moderately entertaining. But it wasn't. It offered nothing new and viewers felt as though they were watching recycled material from an abundance of other movies mixing live action and animation.
That being said, the adventures of the little blue guys as they faced off against the evil Gargamel grossed a whopping $563.7 million, having cost $110 million to make.
This figure saw the making of a sequel which had a similar budget but grossed $200 million less than its predecessor. Sadly for the guys at Sony and Columbia Pictures, audiences definitely learned their lessons from the terrible first movie.
8 Fifty Shades of Grey ($568.9 million)
If ever a film got by on hype alone, it's this one. Fifty Shades of Grey was a phenomenal success as a series of books, despite questionable literary. A film adaptation was inevitable, and perhaps it's unsurprising that it met the same fate as the books: Terribly written, poorly received by critics, but wildly financially successful.
Months of anticipation and build-up - particularly amongst the book's female readers - led us to this year's movie release. Directed by Sam Taylor-Johnson and starring Jamie Dornan as Christian Grey and Dakota Johnson as Anastasia Steele, it was a massive disappointment.
It was criticised for its lacklustre dialogue, its arduous pacing and its questionable acting.
In spite of all that, from a budget of just $40 million it has grossed a huge $568.9 million to date and two sequels (Fifty Shades Darker and Fifty Shades Freed) have been confirmed for 2017 and 2018.
7 The Hangover Part III ($722 million)
2009's The Hangover was undoubtedly a very funny film. It spawned two sequels (in 2011 and 2013, respectively) and the box office takings gradually increased with each movie. Yet, the comedy offerings got progressively worse.
Having ventured to Thailand for the second movie, the third and final instalment saw the trio of Phil (Bradley Cooper), Stu (Ed Helms) and Alan (Zach Galifianakis) return to the original location of Las Vegas - but the concept was just too silly. It diverged from the formula of the previous movies. Gone were the drunken adventures and subsequent necessity to piece together what happened and in came a dark comedic action thriller.
With the first two movies grossing $467.5 million and $586.8 million respectively the producers may have gotten a little lazy. This one cost $103 million to make, and pulled in a massive $722 million. Somehow.
6 The Twilight Saga: Breaking Dawn - Part 2 ($829.6 million)
The Twilight movies were a cultural phenomenon and a moneymaking powerhouse. They were also, by all accounts, pretty terrible - and that's reflected in their collective critical reception. None of the movies in this vampire franchise have received anything above average reviews by respected critics, and most were received outright negatively.
The five movies have, however, grossed a worldwide box office total of $3.345 billion and the best-performing of them all was the final instalment - 2012's The Twilight Saga: Breaking Dawn - Part 2 - which grossed an astronomical $829.6 million, having cost $120 million to make. It should be noted that, critically, it was the best-received of them all, but that reception was still far from great.
For a bunch of movies starring incredibly boring actors which focused on ridiculous sparkly vampires and extremely miserable humans, that's pretty good going - especially considering that the worst-performing entry in the franchise still raked in $392.6 million.
5 Spider-Man 3 ($890.8 million)
Spider-Man's cinematic adventures have been mixed in terms of their quality and success. The fact that the character has now been recruited into Marvel Studios' Marvel Cinematic Universe is testament to that fact.
With five movies to date (Sam Raimi's trilogy between 2002 and 2007 and the two ill-fated Amazing Spider-Man movies in 2012 and 2014), the worst received of them all was the third instalment by Raimi - and yet it's the highest-grossing of them all as well.
None of the Spider-Man movies have performed badly financially - it's the recent Amazing Spider-Man 2 that did worst, with $709 million in takings around the world - and, to be fair, both Tobey Maguire and Andrew Garfield did decent jobs as the Webbed Wonder, but the overly crammed and often farcical Spider-Man 3 took in a huge $890.9 million, having cost $258 million to make.
4 Star Wars Episode I: The Phantom Menace ($1.027 billion)
Overall, the Star Wars prequel trilogy probably wasn't as bad as a lot of people tend to make out - in fact Attack of the Clones (2002) and Revenge of the Sith (2005) got relatively decent reviews - but the Phantom Menace (1999) was pretty damn terrible. It looked good, but the plot and characters - particularly Darth Maul - were very underdeveloped.
That being said, it's the highest-grossing Star Wars movie to date (not for long, however, with The Force Awakens on the way), having pulled in a massive $1.027 billion at the box office (its closest rival is Revenge of the Sith with $848.8 million). It cost $115 million to make.
With that in mind, it's the seventeenth highest-grossing movie ever and one of only twenty to take in more than $1 billion as of the time of this article being written.
3 Pirates of the Caribbean: On Stranger Tides ($1.046 billion)
Pirates of the Caribbean is an incredibly popular movie franchise loosely based on the rides of the same name at various Disney theme parks. In total, the four movies to date (there's another coming in 2017) have grossed a gigantic $3.7 billion worldwide.
Two of the individual movies have broken the $1 billion barrier, with Dead Man's Chest (the second instalment in the franchise from 2006) having grossed $1.066 billion, making it the most successful of the four, and On Stranger Tides (the fourth instalment from 2011) having grossed $1.046.
The latter, however - which sees Jack Sparrow competing against Blackbeard in a quest - is the worst movie in the franchise by far (they've got gradually worse) and has a Rotten Tomatoes rating of just 33%, but is still the fifteenth highest-grossing movie ever made (with the former in thirteenth). It cost $378.5 million to make.
2 Transformers: Age of Extinction ($1.091 billion)
The truth is, the live action Transformers movie franchise has been a phenomenal success - even though Michael Bay has really made a bit of a mess of it. The four instalments have grossed an enormous worldwide total of $3.761 billion, with Transformers: Dark of the Moon (2011) pulling in the largest amount of $1.124 billion on its own.
That being said, while Dark of the Moon wasn't very good (36% Rotten Tomatoes rating), Age of Extinction - the one with the Dinobots - is by far the worst movie in the quadrilogy with a pitiful aggregate approval rating of 18%. Yet it still managed to gross a huge $1.091 billion in 2014, having cost $210 million to make.
Age of Extinction is currently the eleventh highest-grossing movie of all time, behind the slightly superior Dark of the Moon in eighth.
1 Iron Man 3 ($1.215 billion)
Marvel Studios can do very little wrong when it comes to their Marvel Cinematic Universe, with the first ten films in the franchise having amassed a total worldwide gross of $7.16 billion. The eleventh movie, Avengers: Age of Ultron, has already grossed more than £200 million, despite only having been released in a few countries (America not included) for a few days.
No recent Marvel movie has received a lower approval rating than 65% for 2013's Thor: The Dark World. The highest-rated being the first in the franchise - Iron Man - received a full 93% approval from critics. The weakest of the Iron Man movies, 2013's Iron Man 3 wasn't, panned by critics; but comic book fans hated it, as it strayed unjustifiably far from the source material when it came to the main villain, the Mandarin.
It is, therefore, only sixth in the MCU ratings rankings and received a massive fan backlash - but that hasn't stopped it from grossing $1.215 billion at the box office, putting it behind only The Avengers on $1.519 billion in the MCU financial rankings. It cost $200 million to make.