[H2GoKent]

Did a new job this week, customer phones the next day saying 'I'm sorry but I think you have scratched my window'
I politely advise this is very unlikely but I am willing to have a look.
When I got there I explained about the  brushes being made for the job etc my 17 years of doing this without scratching glass.
I also explained how it all works, the water used etc. How I even done builders cleans with cement on the windows and not scratched because I know what I'm doing.
So I look at the window an area about 50mm x 50mm has circular scratches of various depths. Also on the window are some spots of paint.  After further questions it turns out the husband painted the house earlier in the year, and yes he did use a scraper on the glass, but 'not there' apparently.   

After he delivered this line me and him and his wife all stood near for a moment, I did say anything, just let the truth sink in and then said well I'll be in touch to book the next clean. Though I might not bother.
All was friendly and very polite, he knew he'd done it and so did she.

Chancer

[SB Cleaning]

I've had an old bat accuse me of scratching all the windows on her house a few years ago, large farmhouse with old sash windows flaky paint, hadn't been cleaned in 10 years by looks, she was happy as Larry when i left, she then phoned me up  4 days later going ballistic about all the scratches, I calmly explained how the system worked but she said she'd already been on the internet and wfp can leave scratches according to what she'd read, so i then say i will go back to the house and scrub a couple of windows and if it leaves scratches i will be happy to replace all the windows on my insurance, she said no i never want to see you or that system ever again  and hung up 

[Elfyn]

I've only had this happen to me once. A few years ago I was accused of scratching the class on a few panes on a fairly newly erected conservatory. I went to see the custie, explained the process, showed him the brushes etc, but he still didn't seem convinced even though I couldn't see the scratches myself.
I then cleaned the connie glass using trad and he was as happy with that.
To this day, I don't know if there really were scratches in the glass and he'd been on the internet and read about this myth or trading the glass solved the problem.
Never wen't back there again, of course.