I have to say that my biggest guilty pleasure are watching stupid movies that are aware they are stupid movies. Movies that have simple plots or ridiculous plots, but are easy to follow along. As long as the movies put together strong characters and actors who fit the role perfectly, then I can forgive just about anything wrong with the story or the effects. If the actors are having fun with it, chances are I'm having fun with it.
Snakes on a Plane
Half of SYFY original movies
On the contrary, I really dislike stupid movies that try to pass themselves off as something more dramatic than they really are. The actors usually try way to hard, and attempts at meaningful dialogue usually sound good in ones head (or maybe a fanfic), but sound really stupid on the screen.
Just about anything from Michael Bay
Battle: Los Angeles
The Last Airbender
The other half of SYFY original movies