I generally don't acknowledge it. I mean I don't completely ignore the person but I don't make a big deal a big deal about being complimented. I don't really get what the big deal about getting compliments or giving them is (I mean I understand why you'd compliment or want compliments from your significant other, but I don't see the big deal about other people). If it's something that makes me happy then I might smile a bit, but most of the time compliments are inconsequential and probably not very sincere or rather not very accurate or truthful. If someone tells you they think you're nice or something along those lines it might not actually be because you're really nice. I'm not saying they have some ulterior motive. People just seem to think anybody who doesn't treat people like crap are nice.
I think it's okay to shrug them off to be honest. Complimenting someone back seems totally fake, and thanking somebody for every compliment seems a little strange to me. I get that thanking someone is a sign of appreciation, but I think a casual compliment or even comment isn't something to be super appreciative of.