As a native Texan I sure recognized the difference in Mexican food in California and in New Mexico from Texas, and of course in different regions of Mexico itself.
Yep, but the mainstream chain restaurants serve a modified Tex-mex that sells well to Joe and Susie Sixpack.
The only good Mexican/Native American restaurant food seems to be in little holes in the wall where the staff is more comfortable speaking with you in Spanish. But that doesn't always mean good food. I find the best food seems to come from mom and pop places where staff is happy and openly Christian.
/johnny