g_leyser, thanks for this great threat and your detailled answers.
1.) What will be cleaned/exchanged after a guest leaves (e.g. one person staying in a two bed room):
a) all towels (also the - maybe - unused ones?)
b) all beds (also the second - maybe unused - bed?)
c) what happends to unused soaps (most times the wrapped soaps become wet, too).
2.) How did you do the overselling?
Did you manually look at any night and make adjustments? Did your system do the overselling and the staff only made several checks, e.g. "critical nights". Who is responsible for the overselling rate (e.g. 5%)?
Did you have established a procedure how to cope with guests that got no room anymore because the over-selling was too high (e.g. verbal excuses, money/vouchers)?