My usual outfit:
Steel toed shoes - most comfortable way to spend an hour or more standing in one place. Of course, since I wear them whenever I do jobs around the house, they're dirty and worn.
Old blue jeans, t shirt, and maybe a long sleeved shirt - I don't wear my best clothes because I don't want to get oil or grease on them. I don't want my good clothes to start smelling like hoppe's or gunpowder.
Hat-whatever one I find first.
Wearing 'nice' clothes would waste my time (extra cleaning involved) and possibly ruin my clothes. So I wear what is comfortable and practical. I don't look slovenly, but I'm not going to get on the cover of GQ by a longshot. I'm there to shoot my guns and have fun. I am not there to impress anyone or alter the perception of gunowners on the odd chance a camera crew walks in.
If someone has a problem with the way I dress when I enjoy my hobby, that's their problem, not mine.