More thread creep- I never have had a bad tamale from a street vendor, either in NM, CO or in Mexico. I mentioned San Lucas in Baja- I was with a tour party off a cruise ship and we stopped in the little plaza so they could buy trinkets. I bought a tamale from the vendor there and it was good. I think everyone expected me to come down with Montezuma's revenge, or at least Pancho Villa's hop, but no problems.
My only genuine case of food poisoning was obtained in NYC.