I have been referring users asking for support of premium themes back to the authors support forums. Unfortunately some premium theme authors don't provide very good support.

I like the idea of only providing support for repository themes. I always try to tag them if I don't have time to answer and hopefully the themes author will see the question. In fact I just had the idea of proposing to the new theme review list to ask theme authors to make some sort of commitment to answer questions about their theme on the support forums.

Example of a specific theme question;

How To remove black hovering bg from the menu of 2010?

Example of non specific theme question

procedure question about modifying my theme