100+ night per year here. I'd say ~5 hotels a year are unsatisfactory, for a variety of reasons, mainly noise, ineffectual A/C, something not working or other guests.
Maybe 1 of those stays has a cleanliness issue. I'd say you are unlucky.
My grossest cleanliness issue was grabbing a large towel from the pile of "clean" ones shaking it out and and being presented with a nice long skid.... I always inspect towels very carefully.