Thank you for your responses. I just wanted to get a take on other people's perspectives b/c I have said thanks for rep points before (in PM) and never heard back. So I was worried that thanking people was bad. OK, I know, that is a scary view into my tendency toward paranoia, but that's b/c you don't quite get what is going on in other people's heads on the internet.

I always explain my points. I have only given negs once or twice and for glaringly offensive comments (like, "you probably killed your snake and can't confess"). My only regret is that I wish I could remember more to give pos rep points where deserved. I often forget, but those who get them from me REALLY deserve them for a good job.

Also, one more idea - I feel felt that a pos rep point from a well-respected member or a mod/admin is like GOLD.