Remember that the internet is a massively powerful thing these days. I know custys can be stupid and annoying but they hold the power.
i dont agree with this statement in regards to window cleaning TBH.
some of the biggest businesses on here, making decent profit have mediocre to bad online reviews.. average ratings of 3/5 and some with very bad reviews spelled out by ex customers on google.
this doesn't mean i think you should argue with customers and throw dirty water on windows.
of course you shouldn't, and you must have been pretty wound up to do that.
like previous have said here, most of this can be avoided just by communicating clearly with enquiries when you first speak with them. however, some people are very difficult to deal with and are infuriating for sure.
saying that, most people are reasonable enough if you can calm the situation down, listen to them, and treat them with respect.
it sounds like you were having a bad day to be fair