I flush when I get time, usually about 3 trips out of 10 per season. I've been doing the GEO method since we got it (6 years) and have had zero problems with odor or dumping. I agree the best "flush" is a drive to the next campground with 1/4 tank of water and chems. If you are getting odors you maybe flushing the toilet when the exhaust fan is running or your air admittance valve under your sink isn't sealing like it should. There isn't a septic/holding tank on the planet that doesn't stink. Only a question of how well it's containing the odors.
FWIW, the gray tank ain't no bed of roses either.