The safety of street vendor carts is pretty easily judged. If it's a popular cart that the locals flock to, I think it's reasonable to follow their lead. Same for popular restaurants: if it's packed, I take that as a good sign. Of course, there are food safety risks even at popular restaurants--you never know if you will draw the unlucky number that night. But I think your "toilet" analogy is way off base. I'd rather sample local food with gusto at the risk of occasional traveler's diarrhea than live on familiar foods that have been cooked to death for me. The food is a big draw for me when I travel. If the food aspect of a dive trip didn't matter to me, I'd probably go to, say, Roatan or Cayman. But I love Mexican food.
Hey it's your body and your vacation and your business; but you probably realize that you may be risking more than an inconvenient case of traveler's diarrhea - but again it's your decision.
But the toilet analogy is not off-base and it is not just my opinion. These diseases are transmitted by eating food and drinking water that has been contaminated with human and/or animal feces.
That's not a myth or a theory; it's an inherent part of the life-cycles of these micro-organisms. It's how they survive and find a new host so they can continue to reproduce. When the host's body starts to make antibodies to attack the invaders, it's time for them to move on and find another susceptible host.
And my concern about street vendor carts is not just because my friend (the street vendor gourmet!) has suffered permanent neurological damage after acquiring Toxoplasmosis in Mexico; below are the Center for Disease Control's Travel Health recommendations for Mexico and they specifically advise against eating food sold by street vendors.
I love visiting Mexico and I enjoy trying new things and local flavors too, but I don't buy them from street carts - but that's my decision.
I'm honestly not trying to dampen your fun during your upcoming vacation. I have some professional expertise in this area and I was trying to share some information with other interested individuals.
I truly hope that you have a great trip and a really good time and you stay healthy. I hope that for all of us.
CDC Travel Health Recommendations (Mexico):
Learn actions you can take to stay healthy and safe on your trip. Vaccines cannot protect you from many diseases in Mexico, so your behaviors are important.
Eat and drink safely
Unclean food and water can cause travelers' diarrhea and other diseases. Reduce your risk by sticking to safe food and water habits.
Eat
- Food that is cooked and served hot
- Hard-cooked eggs
- Fruits and vegetables you have washed in clean water or peeled yourself
- Pasteurized dairy products
Don't Eat
- Food served at room temperature
- Food from street vendors
- Raw or soft-cooked (runny) eggs
- Raw or undercooked (rare) meat or fish
- Unwashed or unpeeled raw fruits and vegetables
- Unpasteurized dairy products
- ”Bushmeat” (monkeys, bats, or other wild game)
Drink
- Bottled water that is sealed
- Water that has been disinfected
- Ice made with bottled or disinfected water
- Carbonated drinks
- Hot coffee or tea
- Pasteurized milk
Don’t Drink
- Tap or well water
- Ice made with tap or well water
- Drinks made with tap or well water (such as reconstituted juice)
- Unpasteurized milk
Take Medicine
Talk with your doctor about taking prescription or over-the-counter drugs with you on your trip in case you get sick.
Eating raw dairy products and vegetables in Mexico can put you at risk for serious infections.
