I always charge them my time and travel if it is on the inside, I loose the job mostly, but you will loose it sooner or later from them being embarassed.
One I still do trad told me one day "It takes a special 'kin talent to leave a perfect square of dirt in the middle of a patio door."
My reply, "It takes an even more talent to leave it on the opposite side to what I work."
He took it well and is still with me.