As you all undoubtedly know, the stati'ns hygiene isn't often put on the highest priority. To simulate more the importance of actual good hygiene, I would suggest some things to perhaps be changed or added:
Currently there is a score penalty linked to the amount of UNcleaned tiles. This means that somewhere, if I am not mistaken, the amount of uncleaned tiles is registered. It would be nice if there would be an increased risk of infections spreading, the biohazard event increasing in frequency.
I would also like the more deadly diseases come up more often. The jungle fever one, I haven't seen in action ever, for example. This would actually render the janitor's job more important. Currently it's more about an environement being pleasing for the eye than the actual hygiene that the janitor is called.