It never occured to me that people wouldn't use the top sheet until Mum had friends visit that didn't.

This may be a rude question, but how often do you non top sheet users wash your doona covers? When Mum has those aforementioned friends visiting she always washes the doona cover (and the top sheet that they sleep on)
Probably once every 3 weeks, sometimes 4 LOL. I must sound like a grub but we have showers during the night so dont know how dirty the doona covers can get.

Although i must admit, i only have dark colours for linen. What you cant see wont hurt right? LOL

Plus my BO smells like rose petals anyway LOL