If one is going to "reclaim" the term gay, wouldn't one assign it the original definition of "light-hearted and cheerful"?
In any case, the practice of taking terms used to describe minority groups and twisting them into insults is surely left behind once a person matures. When I was back in primary school, one of the more common playground insults was to call someone else a "spastic" (even though we hardly knew what the word meant) which, upon reflection, was a pretty awful thing to do. Nowadays, if a mature-aged person were to use that term as an insult, I'd see a big neon sign on their head flashing the word "immature" (or worse) and treat them as such.
Now, if someone happen uses the word "gay" in a derogatory sense once or twice on a message board, then I don't think there's too much of an issue. However, if someone is trying to "reclaim the word for the assholes of the world"... then see above. No offense intended here, but I thought it was worth posting my stance on the subject.
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Unfortunately I haven't heard much of Stevie Wonder's music, though what little I have heard was great, in my opinion. Definitely an artist whose works I need to listen to more.