I don't really care about Karma on this site (mine or other people's). If I did I certainly would have checked this comment earlier ;)
If people post for Karma instead of for content, IMHO it is their problem. It won't make the site much better, but it won't make it much worse, either.
It is perfectly possible for both of the following to be true: (1) The community gets what it deserves. (2) Some of the people giving it what it deserves are behaving shamefully.
(At least, it is if "gets what it deserves" means "gets something it's got no right to anything better than" rather than "gets exactly what, in some kind of best possible world, it would get".)
Having said which, I don't think it's all that shameful to write what you think will get the most votes. But I'd rather you didn't.
I know it works on me. I don't write the best comments I could, I write the ones I know will be upvoted.