A lot of times I see people saying things like "I have never heard of..." or "Wikipedia search didn't show anything about..", etc. as evidence that a certain fact is not true. 

Maybe it's because this is politics and everyone who cares to opine on the subject believes themselves to be educated enough to have a right to understand everything that is being said, but this does not elucidate any topic... ever.

My position has alaways been that if there is something I don't know, that is something that can be said about me. But people seem to claim that their ignorance of topics can be evidence of something about other people. This is never the case.

Is there an appropriate procedural way to handle this? Pointing out people's self-professed ignorance usually gets taken as a personal attack.