WDW resort rooms are adequate, but not especially clean. I usually go with supplies and spend the first hour or so of my vacation cleaning. I know that you shouldn't have to do this, but I am happier knowing that it is cleaned. I am not a 'white glove' person, but I do like to know that my living quarters are safely clean. I have seen housekeepers 'finish' a room in less than 10 minutes! It takes me longer than that to do the bathroom alone!
I have found bathrooms not only insufficiently cleaned (with hair), but with unflushed toilets (either from previous guest or someone else). In the room: Dust, partially eaten small scraps of food on the floor, small pieces of dirty clothing left behind under the bed, dirty marks on the wall - you name it, I've probably seen it! LOL! Generally, though, rooms are fine, at least as far as you can see. Perhaps the worst that you will note is dust in corners or on surfaces not usually accidentally 'dusted' by guests.
For me, I have seen enough that I don't trust that anything is clean just because it looks that way. We NEVER go barefoot in a hotel room. We always wash coffee perk and glasses before use and we always clean surfaces of things that we use ourselves.
To be fair:
Housekeeping staff only has about enough time per room to make the beds, pick up the dirty towels and wipe down the bathroom. I don't think that they even vacuum every day anymore.
There has been an overall decrease in service in WDW over the years. It is most visible, IMO, in the level of cleanliness that you can expect. I remember the massive numbers of people around picking up garbage and cleaning the public restrooms. The housekeeping staff always vacuumed the room and put clean sheets in the bed daily. Those days are gone. I guess.