Although incall I have learned to direct to the clean towel (away from my damp one), and pass soap, outcall I am often looking for a towel and sometimes soap.
Many seem to just use shower gel for their shower, but nothing at the sink. Regulars put out a clean towel for me, anyone new I tend to specify. Sometimes in hotels the punter has only booked for one, so only 1 set of towels, I've also been directed to use what is actually the bathmat, apology made by client when he realised. I do try to carry a lightweight towel and soap, but do ask for towel and soap to be available when accepting the booking. I do this in a 'Don't mean to insult you but I've had a few instances of dripping hands searching for towels which are kept in a cupboard unknown to me (plus I don't look in other people's cupboards without being told to do so)' way.