I used to beat people at double dash just using my feet. It was kind of a party trick.
holy crap I thought I was the only one! but my games of choice were shooters. joystick in the arch of my feet. got good at hitting buttons accurately with the bottom side. and bent a metal coat hanger to work the L1 L2 R1 R2 buttons and worked them with my toes. never figured anything out for start and select but you never really have to hit them often in games so it never bothered me to just hit it with my hands.
in the early days of CoD's on ps3 (MW, WaW, MW2) I would play 4 player split screen or 2 on 2 private match and take a side by myself (2 controllers one with my feet the other with my hands) and generally win ~70% of the games.
as for the original post it really has not been all that possible until relatively recently. most games that let you pick the button layout you want condense it to 3 or 4 styles. true button randomization has really only happened in the last generation on consoles so no I have never randomized the button layout.