I just got back from Shanghai and yes, I took my shoes off on the 13 hour flight from Shanghai to Chicago. I kept them on from Chicago to Houston though. Just a side note, Yao is on a lot of posters in Shanghai. There were a lot of Rockets fans whom I spoke with while there. Surprisingly they still follow the Rockets. I had a great time to say the least. Karaoke bars are great! Hehehe.
I wear the comfiest shoes I can on trans Atlantic flights. I make Damn sure the shoes are big and I loosen them up onboard. My fav are Jordan 13's. They fit like slippers after I loosen the laces.
I only take my shoes off when I'm on long distance flights and I put the throw away socks from the amenity kit over my socks. I really do not like it when someone sticks their bare feet (no socks) anywhere near me on flights. In fact, I just don't like having people next to me on flights. Sometimes, it's unavoidable, though .
Is leaning your seat back considered improper? This is the second time in a week I've heard someone mention it...never realized it was an issue before. It seems like everyone leans back. It doesn't bother me when the person in front of me does it, and I'm 6'3".
I lean back all the time. I also use my laptop, but jimmies aren't rustled in the event I'm leaned back upon. It's all part of the game... What really bothers me though? Fat or extremely broad shouldered people. No stopping that onslaught. Hope for open seats... Or else, stand your ground and prepare to be surrounded.
I always take my shoes off to masturbate so the answer to your question is yes, I do take my shoes off on the plane.