if there really bad ill charge at least 50% more,sometimes double.
the problem with just starting up youll find a fair few who will just have a one off clean esp if you ve canvassed them.
ive had it done to me a fair few times over the years!absolutely minging windows/i clean them taking me twice as long as normal/then they cancel the next clean or wont answer the door!
im a bit older and wiser now!!
best wishes
dazmond