I liked it. It have a very sound game mechanic in its foundation.
Some quick notes:
- seats cleaning gets quite tedious with time because of all that pixel hunting, perhaps that action could be simplified (like, just click on a seat)
- some time pressure could help with the challenge aspect (some waiting countdown timer for visitors?)
Overall it's good prototype with a working idea that can be scaled out into a solid casual title. So if you won't do it, then let me do it myself ))