Like Barbara said the waste system is sealed except for the roof vent/s. If you have odor that isn't coming from sewer gas being drawn into the RV somehow, you have a problem that needs to be addressed.
Waste tanks stink no matter what you put into them. To me perfumed poop still smells as bad as poop.
There are a lot of out here that use nothing but water and have no odor problems, In my case 11 years of full timing with no odor problems.
Some things to check:
Water in all traps,including washer if you have one.
Air admittance valves on all sinks sealing after dumping.
Roof vents not clogged with wasp nests