I'm going to be 25 and I still go in Hot Topic (I rarely buy anything, but I just like to browse). When I go to Pittsburgh, my aunt who is 40 always love to go in with me because she says she has an excuse to go in. The only thing that really bothers me with clothing/style is seeing 35+ year olds wearing Hollister/Abercrombie.
Oh and my mom's 50, and one of her favorite bands is Weezer and we listen to Alt Nation on Sirius when i'm in her car. I don't ever really think you're ever too old for a certain genre of music.