Sure, nobody actually runs a Turing test. It's too hard. If a real Turing test were ever passed there wouldn't be any dispute. They're ALL restricted versions where the judges go easy on the computers.
The 13 year old gambit isn't the problem though (it's the judges). In fact, it suggests all sorts of strategies for the judges to trip up the computer. I just had a quick conversation with Eugene where I told him a story about a pretty girl asking a guy to go to the movies, and the two of them sitting right at the back. He changed the subject. Obviously not a 13 year old boy.
I agree with you, a proper Turing test is the best, possibly the only way we currently have to assess an AI. But if you have a computer that you think is at the level of a five year old, for example, find some child psychologists and let them talk to it and some real five year olds. Or thirteen year olds. Or adults. Age doesn't matter.