Not true. Most of the Spanish spoken in the SW US is atrocious.
Most of the "Spanish" spoken in the US wouldn't be recognized as such by people from Spain. While, on the surface, it's somewhat similar to Spanish, it was bastardized in Mexico and further bastardized when "Mexican Spanish" became "Americanized Mexican Spanish" here in the US.
My high school Spanish teacher is undoubtedly rolling over in his grave at the "Spanish" I have to use to be understood.