I actually had to wear one this week when I visited the Optician. I didn't have to wear it in the shop, just while he was carrying out the eyesight test. Out of curiosity I decided to walk from the car park to the shop with it on, just to see like, but I couldn't see, my breath coming out at the top end where it was covering my nose, fogged up my glasses and I was struggling to see where I was going. So I took it off for my own safety.

They can please themselves, but like BT I won't be wearing one.