[NT!]

i would agree that this could be mildly annoying for the mexican guy who is here in the states and speaks english. i think it's a little different if you are in someone else's country and try to speak the native language (even if they probably speak english), that shows some respect / desire to learn local ways, etc.

one strange permutation of this that i have encountered is when there are several employees with different levels of english proficiency. for instance, i have been to a couple places here in NYC where there is a guy making sandwiches who has minimal or no english (maybe just enough to take orders, maybe none at all), and the cashier will be fluent.

(my spanish is pretty decent and my accent is good, although i speak much better than i understand).

if i need to make a request or ask a simple question i will ask the guy in spanish, or sometimes ask in english first and then translate if he doesn't understand. sometimes, rather than respond in spanish, the guy will actually tell the counter guy what to say, and the counter guy will translate it into english for me, even though i asked in spanish.

this is also something that some guys will do if you ask a question in spanish without being prompted. they will answer in english because they assume you won't understand. this makes sense because a lot of people can actually piece together a question ok but native speakers are too fast for them or they don't get the dialect at all.

anyway, at first glance this new pet peeve is kinda silly, but when you think about it, it actually makes sense that this would be irritating, because experience tells the cashier that if he answers the kid in spanish the conversation will take twice as long. he's not there to give language classes, he's trying to sell some [censored] sandwiches.