This has been discussed before and there were many great comments. After the first week I text the guest I will be dropping off fresh linen and towels. I ask if they would like me to change the bed and they usually decline. I then request they place the dirty linens and towel in the hamper and place at the base of the stairs. While in the area I change the trash and put the clean towels in the bath. This gives me a quick glance of the conditions. I have never had any problems with my monthly guest after starting this spot check routine.