Do you honestly believe in Karma?

Let me explain.

I believe if someone is generally bad natured and a truly mean person, that person is going to get "it" back to them because I do think you reap what you sow. (gosh, I had to look that last word up.) If you are a fucking terrible person to everyone else, you aren't going to get a lot of goodness back atcha. But if you are good towards everyone, people are going to be good back to you.

Do I think bad shit happens to good people? Sure. So I think good stuff happens to bad people? Sure. But in general, I think the more bad shit happens to bad people than good shit. And vice versa.

Do you think if a generally good person does something really shitty - will they get that shitty thing back to them automatically through Karma? Does all the bad stuff = bad doings and good stuff = good doings? Does karma mean it will all eventually add up?