In the book Speak, why are people nice to Todd Ryder?

Despite Todd Ryder's being, in Melinda's words, "greasy, sleazy, foul-mouthed, and unwashed," everyone wants to be nice to him. Why? Because, as Melinda discovers, Todd just happens to be the official photographer for the school yearbook. Naturally, everyone wants to get good-quality photos in the yearbook, so they figure if they're nice to Todd, they'll end up with a flattering portrait. If they're not so nice to him, on the other hand, they might just wind up being made to look really bad. Super sleazy Todd certainly has it within him to make that happen.
For Melinda, this is yet another example of how the popular students are all obsessed with their image. They're so shallow and vain that they will fall over themselves to be nice to someone that no one really likes, just so they can look good.