I've noticed a weird thing. Which I'm not sure I'll even be able to describe.
It's possible for me to speak either "naturally" or "artificially" - natural language is lazy, and uses slang and colloquialisms to get the point across with as little effort as possible. However, "artificial" language is the result of putting effort into being more articulate, and avoiding habits like "ummm" and "like, this, like, that". You'd think people would prefer the latter, but I've noticed that there is some kind of block, which prevents people from comprehending it. If I start speaking very well and articulately, I just get people nervously pretending to understand what I'm saying: "yeah, right.... *avoids eye contact*". However, if I start being sloppy and colloquial, suddenly everyone's attention is sparked, and people listen closely to what I'm saying, and become engaged in genuine conversation.
It's just baffling to me, because personally I prefer listening to really good speakers. I don't know. Maybe it's intimidating, or irritating, like I'm making them feel stupid, or attempting to.