I know it's mixed but Ugg recommends them be worn without and I have not had any problems with mine smelling or getting nasty and I have worn Uggs nearly every day in the winter since I got my first pair in 2005. So Its how I wear mine. Anyways we went on a family trip two weeks ago to a resort in Mexico. Now it has been a while since we went on a trip where we were flying since its hard with the two kids. Well they are old enough now and were on break so we went. It was me, husband and our two daughters(10 and 13). It was a really cold morning so me and the girls wore our Ugg boots which turned out to be a mistake. We checked our bags and got in line for security. We were half way through when I remembered that we had to take our shoes off. So we had to take our Uggs off and walk across the nasty floor barefoot. I wiped our feet off with a small towel I had in my bag and thought we were fine after. Our feet were comfy on the plane but I forgot one more thing... Mexico Is a hot place. It was 90 outside and with going through customs, getting our luggage, finding the shuttle and how crowded it was we, couldn't change. The shuttle driver throw our bags in the back and rushed us to go. The shuttle ride was two hours with barely working AC. We couldn't change out of our Uggs until we got to our room. Then we were there for a week and bought some shirts and stuff. Well our bags were already packed tight to save space and with the extra stuff we couldn't fit our tall Uggs in.... so we had no choice but to wear our Uggs on the way back... Well my feet were happy when I had them on back home where it was below frezzing.