How much extra money is it making you to get them perfect?
How much extra time are you spending?
What is your method?
How many callbacks have you gotten for dirty tracks and sills?
Mind you, I like me a clean tracks and sill. Track brush, small pump sprayer and sponge. Some have recommended a paint brush.
But, no, the customers usually dont care. During estimate, the phrase, "to a reasonable degree" helps set their expectations.