I often remove my shoes, or more often open toed sandals, as soon as I get seated before taxi and takeoff. If it is cold outside, I might leave them on until we are safely airborn, just in case of an emergency evac situation. Funny, I just thought about that yesterday flying out of IAD with my sandals off. It was pretty cold out there at 8am.
I'm wondering if excessive foot odor might have been the issue? I have, at times, removed my shoes, smelled my own foot odor, and quickly put my shoes back on so as to not offend my fellow passengers. I don't think the OP has addressed this possibility yet...
Common courtesy should prevail at all times while in the aluminum tube!
JB