(Accepted & Recommended)
A tip is defined as a gift or small sum of money given for a service performed or anticipated. Tips should be earned! Why should someone who gives you poor service be rewarded? On the other hand why not over reward someone who has gone out of their way for you. Not tipping or a low tip for poor service would indicate to the establishment that they need to improve their service. If the service is excellent and a tip is forgotten, then it could label a person as a cheapskate, and this could reflect poorly on their home country or nationality. Most would want to avoid this scenario.
In Mexican Restaurants, the accepted tip rate is 10 to 15%, just like in the US or Canada. Some exclusive restaurants include tips on the bill. Check your bill before leaving a tip on the table. Never refuse to tip the server just because the meal wasn't up to your expectations. Instead inform the manage, as they would appreciate knowing that there was a problem with the food. Side Note: Some restaurants only process one bill per table which for groups of friends creates financial confusion, as someone has to pay the whole bill, then collect from each friend after itemizing what each person ate. Ask for separate bills before ordering.
The 15% rule can not be applied to hotel maid tips, as it would be too much. Say you were paying 800 pesos for your hotel room, then a 15% tip would be 120 pesos (about $9 per day). A 5% tip rule would be more than generous at most hotels. Let your conscience guide you!
Hotel maids should be tipped daily for making up your room. Here it's good to tip in advance before they render the service, so its an honor system. Leave the tip money on the pillow or leave a note, so the maid will know it is a tip. They often don't take money that is left on a bedside or kitchen table. Some prefer to tip the maid in person, thanking her for excellent service.
Don't assume that because you are paying an overly high room rate, or are staying at an all inclusive, that you don't have to tip your maid. In Mexico the income level of labor employees is quite low, so most depend on tips as part of their income. Be as generous as you can.
Personnel that you should tip: Waiters/waitresses, hotel maids, baggage handlers, grocery bag persons, gas station attendants. Taxi drivers are not normally tipped in Mexico, as taxies are not metered, but may be tipped if they go out of their way for you.