I can't stand booing, especially for your own players. The only time you boo your own player is if there is a CONSISTANT lack of trying. Not getting a hit or living up to some stats they had several years ago doesn't warrant booing. The stupidest booing is when a pitcher throws over to first base, followed by the intentional walk.
The only booing I support is the half-hearted booing of a player who has killed your club, because it's a sign of respect.