How do you feel this bar?

English speaker walks into a bar in China hoping to practice his Chinese*. Chinese waiter walks up to the gweilo hoping to practice his English, and the game begins. A lingo-blogger takes on the heavy challenge of analyzing this linguistic power struggle in a post on sinosplice. In classic linguistic fashion, he devises a rule:

John's Rule For Determining Language:
Given a conscious choice between a number of languages to use for interaction, speakers will naturally tend to choose the common language in which the poorer speaker’s level is highest.

John wiggles by stipulating that "there’s no strict right or wrong here" (all linguistic "rules" require that same stipulation, haha, so what the hell's the point of a rule!!). But John uses this rule to define a linguistic strategy: "if I want to improve my Chinese without all this strife, I need to find Chinese speakers with English worse than my Chinese."

While John evokes communication efficiency as his basis for this strategy, he misses a crucial factor: appropriateness. It's not really appropriate for a customer to use a waiter for language practice, and vice versa. Even though it's effective for language learning purposes, that's just not why bars exist. Once John as customer violates the appropriateness, he's all but invited that waiter to do the same. At that point, all rules are off, it becomes a linguistic jungle with each speaker fighting for survival.

Unfortunately, neither John nor I could find any academic research on this topic (I found tons on inter cultural pragmatics, but nothing obviously on this particular situation). I suspect it's out there, it's just hard to find. What terms should I search for? Hmmm, it's an odd one, no doubt.

*The blogger did not specify what dialect, though Mandarin is likely.