Yes.. got a Chinese woman who has been inspecting her windows with a fine tooth comb the last three cleans lol. and every little bit of mark she will let me no, but now there starting to come up pretty good they where just leaching water from the top rubbers.
Apart from that no one really bats an eye lid and at the end i just explain its pure water the windows will dry clear and in this weather if you show them a bottom window they will probably be near dry the time you have finished so you can show them the results in a way.