I have always worked in some sort of service/retail business..
I have found that those who choose to speak spanish are beinbg rude..
Rudeness (also called impudence or effrontery ) is a display of disrespectfulness by not complying with the social "laws" or etiquette of a group or culture.
When I was working It does seem rude whern a patron will speak to you in English, then turn to their partner & speak in Spanish. It's like wisperinb. If you feekl the need to whisper ya probably should not be saying it.
although I believe in social justice, I do NOT believe in special treatment/catoring to those who refuse to learn.