What is theproblem that Miss little Sunshine dealing with?

The problem that everyone in "Little Miss Sunshine" is dealing with, is actually self-esteem or self-worth. Grandpa Hoover is into pornography (which is considered by some a self-worth issue), dad Richard Hoover lacks confidence in his career as a pitchman (salesman, just the opposite of what a salesman needs), Dwayne the brother is a teen dealing with his value generally (and you'll remember doesn't speak until he finds that his value is in protecting his sister), mom Sheryl is dealing with whether she's a good enough and supportive mom, and of course Olive is dealing with thinking that only if she's a pageant contestent is she pretty and of value -- and she is purposely made to look "dumpy" to boot. At least that's my take on it.