Not if you're going to a formal event, they're not. In a casual setting however, opinions will vary. Some will say "no, never, unless you're at the Games". Some will say "sure-go ahead". Personnaly, I don't wear sneakers with my kilts, but I have no problem wearing mine with Chaco sandals and a Tee to play frisbee golf, or fishing.

Bear in mind that a kilt, even if you dress it down, will appear much dressier than you might think. You might well tick off your gal if she feels she needs to change before you go out for a beer and a burger. I'm not kidding: wait untill it happens to you (by the way, don't laugh; it'll just make her angry).

Bryan...what will your tartan be?