Do your any of your girlfriends get pedicures? Ask them about that. Say "Well doesn't it tickle?" - nine girls out of ten - it does tickle, especially when they scrub the bottoms of the feet - that's a great starting point - when it does tickle, i'll say something like "Well, if it tickles so bad, but you keep going back, you must enjoy the tickling." - from their response to that question, you can usually decide if the water is good enough to dive deeper into. I've used this before, and it worked.