"I am curious on what you had to say, anymouse, about the dips. Is that some kind of dance etiquette that I was never educated on?"

It is a safety thing, a style thing, and yes also an etiquette one.

"I used to go to a swing dance club and we just dipped whenever. Here at this dance party in China I NEVER see dips."

Amongst other things, swing dancers carry their bodies differently than ballroom dancers do, and may be more prepared for the possibility. A sudden movement which conflicts with the way the body is being carried is a recipe for injury. Even in a swing context it's still a potentially dangerous thing to spring on someone unprepared - there are lots of women out there with lasting injuries from "suprise!" dips which interfere with their ability to enjoy dancing now.

"So the girls are often surprised about it (and guys too, who cheer when they see it) and sometimes don't even know how to do it."

Consider that this could be as much rolling-of-eyes "what do we do with this guy?" as actual approval.

"At this point after months of going there they know I dip them at the end of a song."

Maybe, with regulars who know your game, but be considerate of those who don't.

"So if they don't want it they just spin themselves out and bow at the end of the song."

And how will someone new know she needs to defend herself against your trick?

"I like my teacher's take on dips as a finish for a song (she is a professor of world dance and ballroom dance at Susquehanna University and runs a studio. She is a professional with very impressive credentials); she would often say that "The girl has spinning throughout the entire song! It is boring to finish with yet another spin!""

This does not sound like the attitude of a ballroom professional who is attempting to teach sound and safe skills - those who are would stress quite the opposite! Remember, in the US anyone can label themselves as they see fit. It's unlikely that the dean of a university dance department would recognize the difference between sound and unsound ballroom teaching, as dancers from other disciplines tend to dismiss ballroom entirely as entertainment / culture rather than a "real" dance form.