I hate the babytalk too, but at least it means they're trying to be "nice", acting in a way that they hope isn't going to freak you out or intimidate you. But then, it just becomes awkward trying to explain that you're not that screwed up, because they might take it the wrong way and get offended that you're rejecting their efforts to accomodate you.
The babytalk isn't the worst thing though, the lack of any credibility at all even when you can demonstrate that you are far more knowledgable than they are, is worse, and even worse still is when other people make decisions for you, forcing you into doing things by exploiting your cluelessness about how to get out of certain social situations.