http://www.shootingillustrated.com/index.php/30209/the-messages-we-send/ Sheriff Jim Wilson has a piece on what our manner of dress and behavior might say to the criminal element. It's insightful and definitely worth a look.
The rest of this post is more of me rambling into the internet (as usual), and can be ignored unless you're particularly bored. I've been contemplating this topic a bit for a while, and now seems like a good time to discuss it since someone else is thinking on it too.
I'm basically the worst concealed carrier ever. Sure, nobody will ever see it if I actually care about keeping it covered (I don't, WI has open carry and I primarily conceal as a matter of politeness to whimpering ninnies), but that's the problem. My main/only coat is a calf length Outback Trading Company duster, with a leather bush hat complete with rifle fold to go with. Tactical pants and cargoes are incredibly common, because more pockets and room enough to actually MOVE. Almost all of my shirts are very dark, and a reasonable number are MMA style or feature skulls or dragons or whatever. Trail runners or heavy work boots round out the ensemble.
Top it off with the fact that I'm fairly big (6'3" tall and right around 200 lbs of mostly muscle), a permanent scowl (the corners of my lips actually curl downwards when resting naturally), and close cropped military-ish hair, and pretty much only the willfully ignorant will assume that I'm NOT carrying, even if I don't happen to be.
I've selected my style for YEARS (since about 6th grade on) by what I can fight in. I make a point of having the strength and training to back up the look. And honestly? If someone decides they're looking for trouble, I'd rather they look my way than someone else's; I've made a point of making sure that I'll have better odds of surviving than most.