Keep on believing that, WT...
Do you have any idea how often are those systems actually tested?
Do you have any idea how often airplanes get treated for roaches or other vermin?
At best, an airplane galley gets a deep cleaning once every 20-30 days. That's the level of cleaning a restaurant kitchen should get at least twice a week.
Same thing with roach and pest control. I'd be willing to guess that's still only done every 30-90 days on domestic aircraft.
You probably also believe that all pillows and blankets were washed after every flight, instead of just getting a fluff & fold between flights.
Thank God those were removed. They only got stripped about once a month when the aircraft went thru a periodic cleaning (best practice was every 30 days). And changing out the blankets is a hell of a lot easier than sanitizing the potable water supply.