Accent etiquette - si, oui, or yes?

Oye, this is a daily challenge for many bilingual speakers when they encounter someone who speaks English with a thick accent.  Should you speak to them in their native language (if you know it) or try to follow along in their rough English? Here is my article on the issue in South Florida and what's the proper linguistic etiquette.  The reverse sometimes happens to me when I speak Spanish and the other person reverts to English thinking I am non-Spanish speaker because of my American accent en espanol.