I think you need to know the person you ask for advice, or at least have a good image of the guy.

You need to know if he can be objective towards your music.

There's one thing you can be sure of when asking advices. If someone tells you "it's good man, you play well", there's always a chance he might really think you suck but he's too polite to tell you. On the other hand, when someone tells you you play really bad, at least you know he's honest about it.

Personnaly, I would ask some of you for real objective feedback. I feel most mods and seniors know what they talk about. Even if I'm not a theory buff I can still be objective. So I think the best advice probably comes from other players.