I always take my shoes off on flights and depending on the weather my socks too if i'm even wearing them. I've never understood this foot paranoia- chances are your hands that touch everything are probably more dirty than your feet that have been nowhere up until then except in clean socks inside your shoes.

I was on a flight last week returning from FCO and the passenger in bulk head asked the FA if it was ok to put her feet on the wall and the FA said of course and had no problem with it.

When people come to my house for dinner everyone takes off their shoes at the front door to keep dirt from tracking in.

i don't think feet are any more gross than hands, and probably even less so.