This next one isn’t so much a cultural faux pas as it is a guide to survival. When travelling to Mexico here is one simple tip: don’t drink the water.
It’s not just skipping the water. Make sure to skip ice in your drinks. Also skip any foods that need to be washed, (fruits, vegetables, etc.). Mexican people have naturally adapted to the water, but travelers have not. You will probably be safe at a resort, as they purify their water onsite. If you consume the water, you may face the dreaded, “Montezuma’s Revenge” where you basically puke and poo water for the rest of the trip.