Folding KK Pre-flop

[B1gSexy]

My question is, do you ever fold KK pre-flop?? How tight does your opponent have to be for you to fold KK??

I've dropped 10 buy-ins in last 3 days running KK into AA and I'm wondering if I should have folded some of them. The problem is none of my opponents were overly tight. Some of them had good, solid stats, but not really tight enough for me to fold. At least I thought so anyway.