10 ways to check a room to evaluate whether it is clean.
1. Take off pillowcase.
2. Take off sheets
3. Look under bed
4. Move the Refrigerator and look.
5. Look at the toilet water, flush to see if water entering is clear.
6. See if there is a trap on the drain in the lavatory in the shower, if not there will be smells.
7. Look in the window jams
8. Check above the curtains
9. See if their are labels on the mirrors or toilet fixtures.
10. Is there a "Please Clean Room" sign to post, a Hotel that clean rooms needs this.