I think the only valid complaint is the lack of fresh air (opening windows) in some of the hotels. 5-star or otherwise.
TBH, I think any of us who travel frequently know full well that once confined to the room there is b#gg@#r all difference between a 5 star and 4 star, and even 3 star hotel. Most of the time its the services, amenities and facilities in 5 star hotels, and perhaps the quality (but not necessarily the comfort) of the furnishings that give it the 5 stars. But if you are confined to a hotel room, doesn't really matter how good the spa is, the atmosphere of the restaurants, how well equipped the gym is, the skills of the mixologist, the helpfulness of the concierge, the ambience of the lobby, etc .... it's just a room.