I'm really anal (pun intended) when dealing with my black tank, and have never had an odor in the bathroom.. While flushing, camping, sitting at home, 100+ degree weather, etc.
1) I use GEO and an enzyme digester, since it sits for a month or so in between trips (bathroom used during this time)
2) I fill up the tank to full with the external tank rinser before dumping. Fill it up again, and dump again. Rinse until clear
3) Flush 5 seconds for pee and 10 seconds for poo.
4) I dump before the trip (as mentioned, I use the trailer toilet between trips) and put in 5 gallons of fresh water/treatment, so that when driving, clean, soapy water is cleaning the sides.
5) I dump after camping and put 5 gallons in again so that when driving home, the tank is cleaning itself again.
This sounds like a ton of work, but it's really not. The only thing that takes time is filling the tank, but I'm doing other things at the same time. I set a timer on my phone so I don't forget and 'stuff' comes out the vents :).
My sensors even work like they're supposed to.