Recently there have been a number of reports from tourists who have had problems with taxis from the Jiuzhaigou airport. What happens is one taxi picks you up at the airport and sells them to another taxi just a few miles from the airport. The new driver will tell you that you're new hotel is bad/expensive/dirty/full/closed (oldest trick in the book) and try to bring you to another taxi. If you tell him you've already booked a place or he thinks he's not going to make a commission off you he'll sell you to another taxi (or more likely an unlicensed taxi). Even if you ring your pre-booked hotel the driver may refuse to bring you there. The best thing to do is to ring your accommodation provider and tell them what your situation is. They will be able to help you. If you do not have a phone that works in China you should buy a SIM card. It's cheap and it will help you out a lot.
This is not by any means the case with all taxis but there have been some reports of it recently.