This is a good topic, because of the pictures at the begining = proof
Some have already answered incorrectly, which adds to the proof.
To be sure that 1st floor sills and above are clean, without getting sight of them is tricky.
How do you guarantee something that you can't see the results of?
There is only one way, (or two), you say, "I'll get them clean or I'll come back", or you say, "If they're not clean, I'll come back".
Either way, you better make them clean, that's your job you lazy cleaner you!