Craig
the way I see it is You pay for call, Drive to Customer, Set up Pre Vac, Pre Spray and Clean, Then Set down and go home.
Minimum of 1 1/2 hours work. Most dont complain because most trades around here charge a lot more than that.
I am open with Customers about this and do explain the breakdown of it to them and always try to offer them something else to make it more cost effective to them.