I have walked in and seen money on the counters, and I will still ask if it was put there for me or not before touching, I don't want to ever assume.
A few places have had cash sitting around their place in different locations. It is their home, and they should be able to leave whatever they want around their house and not expect it to go missing.
I've even had the odd occasion, he has a stack of cash and has been on some substance, handed a stack of cash because he was a little too messed up to count correctly, took my fee for 1 hr, and handed back the rest.
A tip is a gift from them, not my place to assume, and I prefer to be absolutely sure it is his intent before accepting. If I have to touch their personals like phone or wallet, to put my purse down, I show them where it was moved to.
Sometimes I wonder if certain people even do it on purpose, to see what kind of person we are. There is no money in 1 time visits I find. The goal is someone wanting you back over and over.