I do agree that they do it to get paid, but some do seem to genuinely enjoy engaging with fans and I think those are the best ones. I have a couple of videos where they said they aren't ticklish, but still found ways to make the videos fun and a few minutes long. In fact, Nick Slater (from Reign)'s cameo is one of my favorites, although he says he doesn't have any ticklish spots. The Josh Flagg video sounds like he didn't really read the request just sent something to finish the transaction. :/ Sorry you've had bad luck!!
Personally, I haven't had much luck with the pedicure question, but it might just be that my wording didn't make them think of being ticklish. Erik1009's suggestion might just do the trick!! Only one way to find out, huh?