i wear one under a big t-shirt at the gym, its really comfortable. i don't wear it out but tht's only b/c it'd make me self conscious(sp) of my far from perfect abs. don't really see a problem with someone wearing it around in the general public , at the mall or w/e. as long as you have the body to suit it.
of course its nasty if some fatass wears one or a skinny kid who makes it look like a regular t-shirt. but tht goes for nething tight. ive never seen neone wearing one at a club, but i agree tht sounds kinda dumb.