Movie acting, on a very basic level, is advanced make-believe. The good movie actors can temporarily make you forget that you're just watching a group of skilled pretenders playing dress-up with bad wigs on a grand scale. The bad movie actors never let you forget that they're acting.
Then there's Angelina Jolie in the trailer for Salt who seems like she's desperately trying to convince you that she's just Angelina Jolie pretending to be a Russian spy by playing dress up in a series of bad wigs. The title of the movie should have been Make-Believe With Angelina Jolie:
Considering that Angelina Jolie looks as if she is being crushed by the weight of that backpack, she's not really convincing as an accused Russian spy who can hoist a man from a motorcycle with one arm (especially since her arm happens to be the width of a carrot stick). But Angelina Jolie would be believable in several roles, namely:
—Angelina Jolie
—A model that looks like Angelina Jolie