OMG, David and Chris actually agreed on something, I'm shocked.;)
We spent 5 to 6 months down in La Penita, Nayarit for 8 years and the only time I ever got really sick was on the way back to the US when we stopped for the night in Guaymas at the El Cortez hotel and RV park. I had Tampeqenia?(sp) in the hotel and it was quite pink in the center. I was quite sick for 2 days.
Some of the best food I ate down there was at the Juves Tiangus at a taco stand. You could hardly get close to it for all the Mexicans there.One of our first warnings about street food was to watch who handled the money and if there were a lot of Mexicans eating there.
I am like Old Biscut, as a young sailor eating off the street vendors in TJ, Subic Bay Hong Kong and Formosa and never got sick, or if I did, blaming it on what else I drank the night before.
La Penita RV park water was good and many in the park drink it, but it made our cats barf so we always bought garafons from a guy who came through the park.