customer phoned me a few days ago complaining that i had badly scratched his living room window,big window too,i thought this is going to cost me,but when i had a look i could see hundreds of deep scratches all close together in a line,as the bristles on my vikan brush are spaced quite far apart i knew it was imposible for me to have done it,told customer that even if i had picked a bit of grit it would only leave one small scratch before being washed away, not hundreds of scratches together, must be sandpaper,wfp no way.funny thing is customer still wants me to clean his windows,so was he just trying it on ?seed of doubt is in my mind