The premise seems to be that bad people must have a way to tell if something is evil. Either that, or bad people are repulsed by anything that isn't at least as evil as they are. Whatever the reason, bad people magically will only associate with things that are bad. Therefore people claim a thing is bad because bad people associate with it.
This is a concept called The Association Fallacy, which often overlaps with Godwin's Law, due to how often Hitler is used for this (also known as Reductio ad Hitlerum).
After all, Hitler has gained the reputation for being the very embodiment of darkest evil, who oozed "pure liquid malevolence" right out of his pores. So, he supposedly would only do/like/own things that are as evil as him. Things like sitting on a chair, wearing clothes, eating, taking a walk, and breathing. Hitler did those things, but that doesn't make them bad. Hitler is not a reason things are bad.
We don't think mass murder is bad because Hitler, Stalin, or other bad people did them. We think those people are bad because they committed mass murder. In other words, this trope is backwards. A thing being bad stands on its own as bad.