The Pirates of the Caribbean game was actually pretty fun. Made me laugh, at least. But this is usually true.
Yes, but movies based off of video games seem to be good (ie. Tomb Raider)
With some few very rare exceptions like X-Men Origins: Wolverine and Transformers: Dark of the Moon. The latter is only good because it was developed by and High Moon Studios who developed War for Cybertron which is without a doubt the best Transformer game ever.
The Lion King and Aladdin video games for the SNES were awesome though. But yes, usually they are horrible.