Based on our more recent trip experiences, I think they do a great job of keeping up given the high volume of traffic and messy guests.
On our trips in 2016 and 2017 we specifically noted to guest services how many times we ran into CMs cleaning the restrooms and that it was a big improvement over previous years when we often saw garbages overflowing, etc.
You can tell when a few guests have been messy vs. a problem that has built up over hours. We have not experienced anything recently where a restroom looked totally abandoned and unattended for hours. Maybe we are going to the right bathrooms!