Worst case scenario, being a legit player, you'll get a message or warning that they'll be monitoring your games for a bit... they find nothing, investigation goes away and from my experience you never get that message or warning again... making me believe they don't consider any report against you legit from there on out.. both CoD devs do this, and both have put me on investigation once and found nothing lol the first Black Ops, and MW2, neither has ever bothered me again no matter how many people claim they reported me for something I'm not doing.
As long as you aren't modding or hacking or exploiting, you have nothing at all to worry about.