I can see where they're coming from because most of the "clean" windows from other guys I see are shotty to say the least. They never take the bug crap off. Soo, I venture to say, my dry toweled windows are cleaner still than 85% of the other cleaners glass is. Because they we're clean to begin with.
My commercial customers are paying me to maintain the cleanliness of the glass. If they're clean and bug crap free that's enough for them. If they're dirty clean them. Why waste time cleaning clean glass when you're already cleaning glass all day anyway?
If they were anal and breathing down my throat sure I'd clean them that's what they want. The truth is they could care less. Show up make them clean and leave. That's the extent of corporate Americas window cleaning world.