Unfortunately, tw's and silly texts are part of the course.
With regards to texts - I always say to anyone texting that I need to speak to them (as I can't be arsed with all the back and forth text this, text that - it does my head in) and in most cases the silly texts never come to fruition, do they?
As for asking for a deposit, that's entirely up to you but I personally never have done. You haven't said if it's for outcalls or incalls but it's a matter of trying to do stringent checks on outcalls beforehand. It's explained here on the site, home page I believe.
I also ask where they got my number from. If it's aw then I ask them to complete a booking on there.
For example, had a call yesterday, he made a booking for today and my gut instinct told me he's a tw so I asked where he got my number from and he said aw so I then asked if he is registered on the site. He said he was, in which case I told him to make a booking using the aw booking system.
Guess what, no booking............
Of course, it's not always like that as not everyone is registered on aw. I find the tw's and silly texts seem to come in groups. You have none for a while and then they all come out of the woodwork and it's so damn frustrating but sadly it's part of the course, groan!