I am sure I could name plenty but to keep the list shorter...
ill just to name all of the movies I have seen in the IMDb Top 250 that I feel are below average at best (i.e. 4/10 MAX) overall (ill separate the movies by score bracket)...
-Fight Club (1999) - 4/10 (NOTE: Fight Club is the gold standard of overrated)
-Apocalypse Now (1979)
-Inglourious Basterds (2009)
-2001: A Space Odyssey (1968)
-A Clockwork Orange (1971)
-Chinatown (1974) (Polanski's other movie 'The Ninth Gate (1999)'(8-8.5/10) wipes the floor with this movie)
-The Elephant Man (1980)
-Network (1976)
-La Haine (1995)
-Memento (2000) - 3/10 (NOTE: I may give this one another chance as it's been a long time since I viewed it (probably mid 2000's or so) and I suspect I probably over-reacted to it at the time in the sense I knew it had a high rating going in and when it fail to be even close I over-reacted to it which is why ill probably give it another chance at some point as I won't be surprised if it goes up to a 5/10, or at least improves from it's current 3/10 score.)
-Inception (2010) - 2/10
-City of God (2002)
-Star Wars (1977)
-Interstellar (2014)
-Casablanca (1942)
-Full Metal Jacket (1987) (basically this movie is only watchable when R Lee Ermey is on screen as shortly after that it's completely boring)
-Amelie (2001) (another movie with the same actress that's much better... Priceless (2006)(7/10))
-Gone with the Wind (1939)
-Blade Runner (1982)
-The Handmaiden (2016)
or another way to sum up the whole IMDb Top 250 from my perspective...
---total movies I have seen = 127/250
---movies that stand out (i.e. I score a 7/10 or higher) = 21 movies (16.5%)
---movies that I mildly like (i.e. I score a 6/10) = 30 (23.6%)
---movies that I gave a Thumbs Up = 51 movies (40.2%) NOTE: this 40.2% figure would almost certainly decline had I seen ALL of the movies in the IMDb Top 250.
so given those facts for me... as you can see the vast majority are overrated with some being highly overrated.
p.s. another thing... there can even be movies among my favorites that I feel are a bit overrated. like say some I give a 7/10 but have say around a 8.0/10-ish or higher average etc.
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Here is my general rating scale to translate the above info...
10 = As much as I can enjoy a movie.
9 = Nearly as much as I can enjoy a movie.
8 = Well Above Average.
7 = Above Average. (My Favorite Movies begin here)
6 = Slightly Above Average. (My minimum score to re-watch a movie)
5 = Average (Thumbs Down) (while ultimately a negative score, they typically don't waste my time)
4 = Below Average.
3 = Failure. (I generally finished watching these but they are just bad)
2 = Boring. (I could not finish watching due to boredom and boring is pretty much the worst crime a movie can commit)
1 = Greatly Dislike. (very little I have seen is THIS bad)
for measure... most movies I see get a 5/10 with a 6/10 being the next most common.
or for those who want my system broke down into very simple terms...
6/10 or higher = Thumbs Up (will re-watch)
5/10 or less = Thumbs Down (won't re-watch(with rare exception))
because that's at the core of how I ultimately judge movies is based on whether I want to re-watch them or not.