I think the great thing about Sacha Baron Cohen is his ability to expose the idiocy of those around him while they unknowingly believe that he's supporting them. For example when Bruno interviews fashion and celebrity critics, through light encouragement he puts them in the false sense of security in making terrible remarks about celebrities based on material judgments. When he's playing Borat in America he fully exploits the ignorance of Americans especially regarding race. Its not always just crude jokes but almost a social commentary: exposing, humiliating and shaming some of the worst people that roam this earth. When he plays Ali G, his aim isn't to make crude jokes and resort to lowest common denominator humor. He simply questions his interviewees to the point of utter frustration in his ignorance. Its hilarious.
His movies though, do occasionally resort to the lowest common denominator kinda stuff which is still good in small doses.
Just saw Blood Diamond finally. Good movie didn't blow me away but its pretty solid. DiCaprios South African accent is awesome! And by the end I really wanted to bang Jennifer Connely. I actually was convinced the whole time that she was Demi Moore until I saw the credits. They look alike.