Not many people can take a drink "neat". I certainly can't, but then again, I'm a bit of a pansy when it comes to my cocktails. The only "neat" drinkers I've encountered have been men, and they're quite an interesting sort. In my experience, "neat" drinkers are gambling addicts, have no relationships with their families, and live in filthy apartments. These are not stand-up guys. I'm not usually one to judge, but when it comes to taking a drink "neat", I kinda do. I just associate the drink with a smarmy booze-hound who won't take no for an answer.
I could be proven wrong about "neat" drinkers, and I hope that I am someday. I'd hate to spend a lifetime judging people based on their cocktail preferences, but for now it's just too easy to do. "Neat" drinkers are easy targets. They're the sort, though, who are unapologetic for taking their drink in it's truest, unadulterated form. They're still not the kind of guys you should introduce to your best single girlfriend or ask to babysit your dog when you go out of town. The dog would end up drinking beer out of a coffee can.
So, if you encounter a guy who takes his drinks "neat", just call him an alkie and run the other way. That's my PSA for the day.