I ordered a "Corona con lima" in Cozumel some years back. The bartender gave me that stoopid gringo look when he delivered the beer. Looking around, I realized the locals were drinking Sol, a local brew. Actually a pretty good beer, and it doesn't need salt and lime.
When in Mexico, you can ONLY drink beer. I don’t trust the water and I know if I drink Corona or Dos Equis, I will be safe.