Are you talking about a specific case or many cases or one hypothetical case?
Many specific cases I have witnessed.

If you talking about a specific player log in and give your honest opinion to the player but be kind enough to explain in which situation the player wasn't a good mentor, if you generalize won't do anything for the rest of the community according to other players the majority doesn't even read the forums.
One doesn't exclude the other, you should know that. What I do or do not ingame doesn't have any influence on what I do or do not in a forum.
And forums are there to discuss things, state opinions, get other people's point of view, exchange experiences. After all, you are posting here aswell, are you not?

To have the context of the situations in which mentors weren't good is also important is just not talk in hypothetical cases and only one versions cause that is for failed judges.
As already stated, those aren't hypothetical cases. You shouldn't assume something simply because it suits you.
I could recount several situations from last week alone but what would that "prove"? Nothing, as it is quite possible that I make things up and judging by your past posts you tend to assume that people make things up.