I did the gutters for one of my customers the other day, and I also clean her neighbours windows, who's gutters also needed done. However she wasn't in when we were doing this customers, so I went back, and asked her if she would like us to do them for her, and showed her a picture of what they were like on my phone. She then asked basicically asked me if I was qualified to do them? she said, 'well your windows cleaners, can you clean gutters?'. I should of said, 'Its gutter cleaning, I am more than qualified, I could teach a 10 year old how to do it in 2 mins', but I was a little more democratic, and explained its a service often offered by window cleaners, due to the the fact the people tend to only get it done once a year, we have cleaned gutters for loads of our customers, including your neighbour. I am sure there are loads of times customers have offended others, so thought it would be a good topic.