Yobit being a scam is no longer an opinion, it wasn't an opinion for a very long time. It's a been a fact[1] for a long time derived from the definition of the word and their continual actions. Very bad example by Tecshare and now by you. Some other entity could have been used as an example of a "scam" that is a scam by opinion.
[1] Empirical proof:
https://bitcointalk.org/index.php?topic=5168200.0.
This still doesn't change the fact you are advocating for tagging people for guilt via association. This is not a strategy that can be universally applied and will by definition result in arbitrary and selective enforcement. Furthermore it does nothing to stop the actual perpetrator and will create massive amounts of conflict as well as open wide the doors for abusing the trust system for ulterior motives. All they have to do is claim what is in their sig is a scam, and boom, excuse for punishing people arbitrarily. This strategy achieves nothing and creates MANY negative side effects.