Depends where you are.
Most of the 'temporary' facilities, on MB, Bleu, KN etc are more like portacabins with proper sanitory ware - never any seats though.
Some sites, Expo for example, have a permanent structure with the hoverbogs.
These days, they all are very clean, within the bounds of a portaloo stuck in the middle of a field. They didn't used to be - one of my worst LM experiences several years ago was going into a permanent bog in the village which stank to high heaven, only to see the caretaker sitting in the midst of this horrendous stink eating a plate of (I think) chicken and chips!! I had to leave pretty sharpish.
Del