i personally try to not look at my actual karma( i find the actual karma system kind of flawed, i mean you get karma for posting videos/pictures in the media section, and for being an active member of the site, but whos to say you are positively contributing to the site), or even care about it, the only thing i do look at is the "what other people rate me" just because i can see what people think of me based on what I say, and if i should be less of an asshole in what I say. I cannot speak for everyone, but for the most part I see people saying +k as an attempt to offer something in return for helping someone out, even if karma means nothing to most people.