I just thought I'd pass on a little lesson learnt. Surely its enough for one person to learn from their mistakes and then pass on the wisdom.
Do not say or do ANYTHING in front of your children that you would not be happy for them to repeat!
Or maybe to put it a little differently, if your child is playing with lego on their bedroom floor while you merrily sketch the outline of her new fairy window overlooking pixie hollow on her bedroom wall and then you take yourself off downstairs to do some washing only to return later and find little replicas of said fairy window on every wall in the room do not ask her why she did it unless you want to hear "but you did it first".
You can't argue with it, you can't get upset with her and you just have to accept that it's all you fault!