Interesting that the clientele at the restaurant, for the most part, appeared to be oblivious of the dancers...whereas I would have probably earned my way into a Thai prison.
It would be beneficial for providers and clients if the "go" or "no go" were apparent at the very beginning, but generally it is a progressive deterioration of the chemistry to the obvious "point of no return" before the session is terminated. It is the prolonged anxiety prior to the termination that can make the failed connection seem more hurtful than it needs to be. As the OP noted, it's just "another one of those lessons in life." Onward!
For whatever reason, bovines have recently captured my affection. However, from remembering my childhood days on a farm, I wouldn't want the responsibilities of caring for one.
I would reply with something on the order of:
"Hey dude",
I'm returning herewith your recent email, as it must have been intended for someone else, and I wouldn't want you to miss out on recovering your $50.00.