Use sitio (stationed) taxis at stands or call for one. Simply do not hail taxis on the street under any circumstances. Two reliable radio taxi companies are Servitaxi and Taximex, which accepts credit cards. If you need a cab but don't speak the Spanish necessary to call one yourself, have a hotel concierge or waiter call you a sitio taxi.
Servitaxis (55/5516–6020 or 55/3626–9800. www.servitaxis.com.mx.)
Taximex (55/9171–8888 or 55/5634–9912. www.taximex.com.mx.)