cheetah isn't dangerous at all. There are two different ways you could get a visit by cheetah:

1. cheetah found something similar to your post on another site. This doesn't harm you at all, it is just an additional information for the reader. cheetah also gives you an upvote then.
2. You are blacklisted by cheetah. This happens if you scammed, for ID theft or continuous committed abuse. But before that you'd get several comments by steemcleaners.