I too hit a mirror the other day whilst filtering It just moved a bit so I pushed it back out, the guy said thank you (seemed very surprised I put it back!) and we both went on our way! I had to stop because it was my brake lever that hit the mirror and stopped the bike! ;D I did feel a bit bad about it though But if I hadn't of filtered I'd still be trying to get home now! ;D

I can fully understand annoyance though, especially when it costs £800 for a new wing mirror. I drive tatty old cars and couldn't care less but I know that's not the same for everyone.