Be very careful of how, and how aggressively, you criticize anyone, their way of life, religion, government or methods of doing business, especially in a social environment. You may believe it is constructive, but until you create a relationship based on mutual respect, this will be seen as very negative (and ethnocentric). If you absolutely have to comment, better to ask why something is done in a certain way, let your hosts explain it, don’t pass judgment.
Form is important. How you are doing it counts, as well as the message. This is quite different from the US, failure to pay attention to the “delivery” may cause more problems than you expect.
If the criticism is specifically related to business processes or results, explain what you wish to achieve, how you want them to modify their actions or processes and why. Focus on the expected results and ask for feedback and their observations on how to achieve the objective in Mexico.
Disclaimer The ideas presented are personal opinions and generalizations based upon 25+ years interacting, living and working in and with Mexico. None of this may be true, use the information at your own risk