Well, it's only because I often go on my lunch break, and I am suit/tie person everyday except Friday. In addition, I've had some of the employees at the various stores I go to look at me like, "are you serious?"
It might because of the SUV I drive, my girlfriend (who accompanies me a lot), appearance, etc.
These days, especially at the larger stores, you see brands of cars you'd never associate with discount shopping. Back in the day, I also had a profile in my mind who a thrift store shopper was; however, in my experiences, there's a wide swath of people who shop at the consignment stores, Goodwill, etc.
One thing I've noticed in the last year: where I live, a lot of the stores are jacking up their prices.
I don't whether it is because of the economy, the research one can do on the net with brands, or the stores getting much better educated with their clientele, but some of the prices I've seen at these places are crazy.