Wow, it's like I've landed on the mirror universe, because I had no idea so many people were so uncomfortable getting compliments: I'm not shy about my comments in real life and I hand out compliments like confetti at a carnival (even if I try and limit myself on-line for the creepiness factor mentioned by sidious). If I see something I like (someone's smile, eyes, or just their shirt), I might as well say it. Maybe there is a cultural divide somewhere, because here it's very common for people to be very complimenting to each other. I don't get tons of them, but I do get them, and it's nice.
Out of the blue compliments are the best of all - if there's no reason for the person to have made the comment (out of polite conversation or something) then I know it's real because otherwise it would have been just as easy for them not to say anything.
Still, I'll blush like mad and stutter, but on the inside I'm smiling.
And because I know that's my reaction - I always try to do the same for other people, and give out compliments as I see them, to take them by surprise.