I flew out of Cancun airport 10 days ago and NOBODY at the airport even asked me if I had paid this Tourist Tax. There are no signs, no alerts, no nothing demanding this tax. By the way, I hadn't paid it yet, since I had gotten contraditory orientations about it. So, in a nutshell, it's either included on you plane ticket already or the Quintana Roo tax agency is doing a terrible job on reinforcing this tax on tourists. So, don't pay it unless specifically asked by an official employee at the airport at your departure!
I agree, they don't do a great job at making sure this tax is paid. I do think though that visitors should try to do their best at paying this tax. As this goes towards infustructure, tourist amenities, creating jobs and such. The airline doesn't collect this tax nor do hotels.
