When assigning a room you will see a few icons if the room is occupied and if it is dirty or clean.
The Housekeeping feature must be enabled for the Inspection symbol to show up on the Calendar.
Occupied: Guest in the room
Dirty or Clean: Based on the Housekeeping status is the Room clean or is it dirty
In order to see accommodation condition in Calendar you need to enable it first in the Housekeeping Add-on menu:
Click on the Housekeeping icon
Click to Show accommodation condition in calendar
Rooms with DIRTY condition will be marked with a red asterisk sign *:
The Housekeeping status cannot be changed on the Calendar
The accommodation condition can only be changed from the Housekeeping page