I live in Big 12 country. I haven't seen a single Big 12 or SEC logo on any item of clothing, flag, car, etc. since
moving here. I have, however, realized that I need to get a BYU polo in order to fit in with all of the other guys around here on game days. We went to a party when Arkansas played Texas and everyone wore their nice polos for Texas A&M, Texas, LSU, Ole Miss, Arkansas, etc... and I was the only guy in a t-shirt.
(and none of the other guys' shirts had any noticeable conference logos on them)