Yes I would be mortified! I stopped hanging out with a friend of mine because her child was a brat. We were at their (new) house one day and I went into the hall to find her daughter and my son, both aged about 4 at the time and the girl was drawing all over the (white) walls. I shouted at them both and her mum came through to see what was happening, I said "I jst caught T drawing on the wall" her mum asked if it was true and the demon child smirked at me and said ' no mummy it was him' (pointing at my son) I was gobsmacked, I said "I SAW you! I stood here and saw you" and she still denied it, her mum obviously thought I was lying by the look she gave me. I turned to my son and asked if he had been doing it and he looked very ashamed and said 'yes mum I did it earlier' of course I was angry and he got a row, but I have to say I was proud of him for telling the truth, he hadnt been seen, he could have denied it.
This was the last in a long line of incidents - I never went back