Years back, CBS "60 Minutes" did an expose on hotel room cleanliness and the results were pretty, eh, graphic. And disgusting to many. This included high end name brand hotels, not just your low end no-tell motels. Using black lights and other tests, they found a variety of stains (yep, those kinds of stains) on almost every surface in the room and bathroom. Light switches, electrical outlets, room service menus, TV remotes, beds, nightstands, carpets, walls, .... everywhere. I don't remember if they swabbed the ceilings but I wouldn't be surprised if some tests showed the explosive power of some guests.
I spend One Hour in a hotel room looking for one thing. They spent 60 Minutes looking for something else.
As far as the APPEARANCE of cleanliness is concerned, I hate to bust your bubbles, but other investigative TV/web/print media reporters looking for easy pieces will use hidden cameras or swabs / tests and so on. That tissue-wrapped or "sealed" sanitized glass in the hotel bathroom? Not always. If it looks clean, they just wrap it back up and put it down. To someone above -- I apologize in advance to the hostesses who truly do use fresh sheets -- if you see someone laying down a "fresh" sheet it could just as easily have been smoothed and folded up after the previous guest left but the seeing the action of unfolding and laying down makes it more believable that it is clean and fresh.
For the record, I have had some disgusting experiences, despite reading favorable reviews.
Fortunately, I'm not a germaphobe