As an alternative to points 1 -8 noted above:
1. turn up on time
2. actually know something about the job you are paid to do
3. assuming you have items 1 and 2 under control don't get worked up (you do not get paid a bonus to care what a checker thinks).
Some time ago I was in a sim ride that the other individual was being looked at closely. The checker briefed me not to assist or lead him and just see how things developed. He was incompetent and (amongst other issues) got lost in a circling approach. That was the fact but he probably told all his mates that he was being victimized.
I have no doubt there are problems out there but remember that there are always two sides to the story.