My problem with Stackoverflow has been that for the majority of the questions I've asked, I'm more of an expert in the subject matter than the people answering the question. Most of the answers I receive are to the wrong question, or are an answer that I specifically mentioned in the question as not being viable.
Examples? I'm a moderator and can delete non-answers. I also have a lot of rep to burn, so I can place bounties on good questions that aren't adequately answered.