I only showered once in a few days while in the US during the colder season. That also has to do more due to habit rather than feeling dirty. In cold weather you don't feel dirty coz you will never sweat and your pores are all closed anyway. You only feel your dry skin and cold. Those talking about water heater probably never experienced coming out of the hot shower into a frigging cold environment. You will be freezing your ass off and shivering for a very long time. The first time was scary as fuck and I though I was gonna die. It really sucks.

Germs multiply quickly in hot & humid weather. In cold weather when your skin is dry and peeling off, can't find any germs.