Well, as long as there's a reason to be in it I guess. I mean, I'm not going to walk around work in my costume all day or anything, because that would be just weird, even though I technically could, but as long as there's somewhere to be, and a context for it, like a party or event.
Some of my circles it's actually less socially acceptable to be dressed in everyday clothes than in a costume, which is kind of bizarre when you think about it, really.