A good Twist Ending is surprising, and seems to come out of left field. You're shocked at first, but then you look back and realize that that's what they were building to all along. It takes a great writer to pull off believable twists on a regular basis.
That doesn't stop less-than-great writers from trying, however.
The Shocking Swerve is a kind of twist made just to have a twist. There's [...] [tvtropes.org]