I agree with you on the maturity issue. However, I have called business before who had their parents answer the phone. We were no longer with that company after that but that is besides the point.
The best one I have ever had personally was one of my clients called my cell because our toll free number forwards to it if I am not at the office. Well I was with the girlfriend and I was busy dealing with something and she answered the phone.
I guess it is a good thing that the customer who was on the other end has turned into a good friend and he thought the girlfriends voice was hot. He told me she needs to answer the phone more often.
Other then maturity do you think that there is something that sperates children of "kiddie" host to children of professional hosts?