Well for me, and I am no Casanova but i know when a girl gushes
If a girl told me she went and there was no excess fluid in the area of my member then I would raise the question
I mean, breathing, moaning (or yelling) twitching and overall vibe of the woman changes when she is about to gush
Along with the normal grab my ass and thrust me in during the momentous occasion.
For me it is a tell even the poeple on Celebrity Poker would pick up