I've been to Mexico like 6 times.
The first 5 times were all excellent trips, wonderful places, wonderful people.
The sixth time, we were all literally robbed by Mexican police officers at the airport who claimed we couldn't leave the country without paying an "exit tax" of $200 USD each, and told us we either paid and got on our flight home or we didn't pay and they took us to prison.
I don't go back to Mexico now.