I have used the Thetford valve lubricant and it works fine. Follow the directions. Simple.
Cooking oil will also work in a pinch. Quit using harsh chemicals, especially those with alcohol.
The use of deodorants is also probably unnecessary if you use the systems properly.
The black tank is vented thru the roof. The grey tank is vented to the black tanks vent (and hencce, thru the roof.) The sinks/lavatories can harbour bacteria/odors in their "P"-traps. Splash a little bleach in the sinks.
Avoid running a roof fan, range exhaust fan, or Fantastic Fan without a cabin window open to releive the suction (which could lead to long-term peace.) If you run an exhaust, range, or fantastic vent fan with the windows closed... it will bring air down the black-tank roof vent and into the cabin...along with all that aroma from the black and gray tanks.