I've seen tails sold at anime cons before, and I can safely say that even the realistic ones were fake. I've noticed that most of the people who are drawn to such things are against the use of animal pelts in that manner. On the other hand, I've never been to AX, nor have the name of the vender, so I can't say for certain.
Another thing to consider are the laws that restrict the sale of animal parts/pelts. They vary from state to state, but I'm sure that both the con and the hotel would honor these since such things, since they can be very sticky legally.