They dont want wrinkled sheets.
Depends on the history of those wrinkles...
That made me think of why I decided to go live with my bf. I studied the guy for a few months just to see what was his "rythm" about doing the dishes, cleaning, making the bed (or not). As it turned out, we have the same point of view on things and when one of us says it's time to clean the appartment, the other agrees without hesitation. Those are the things that bug most couples, but not us. If you have a chance to study your significant other in its natural habitat, you can learn a lot before moving in with him/her.
As for making the bed, like the saying goes, we make our bed we lie on it, literaly. A few seconds before we go to sleep, we place the sheets and lie down. At least, we agree.