They almost always return a greeting, and usually with a smile. Speak a little Spanish, and they will go out of their way to be helpful. The border areas do have problems, but some of the horror stories you may have heard are greatly exaggerated. Imagine the crime stories that could be told about one evening in Los Angeles. Corruption exists, but it is not as bad as you might think.
Corruption exists in the U.S. and Canada as well.
It also keeps taxes low. M exico offers a wide variety of excellent dining opportunities. Any type of food is available, and in the better restaurants, the food preparation, presentation and service are among the best in the world. Prices vary from ridiculously low, to as much as you would pay in a nice restaurant anywhere. If you can speak a little Spanish, you can experience excellent values and a wide variety of cuisines.