Well I guess I'll add my 2 *@#&* worth! First off: I use my toilet for both intended purposes; I keep it far cleaner than even the best campgrounds, and that's why I bought a trailer with a toilet in the first place!
Second: flush often! After three or four "wads" of paper go in, it's time to flush. I hold the lever down 1/2 way so it runs enough water into the bowl to cover the paper, then I put the pedal to the metal, and down it goes. I've found doing that - combined with the normal amount of liquid waste - keeps the solids (including paper) in suspension long enough to start breaking down. Third; (as previously mentioned) if you're using a sewer hook-up, leave the valves closed until your tanks are about 3/4 full. Leaving them open allows the liquid waste to drain off too quickly to carry the solid wastes with it. Fourth: use a good black tank chemical. If you're worried about the environment, use one with enzymes rather than one with formaldehyde. Fifth; ice can be an effective scrubbing agent if it is used after
the liquid is drained off. Yes, Mildred, ice floats! So drain the tank, add the ice, drive around, add some water and dump. Sixth (and most important): drain and clean your tank whenever you leave a campground. If you're at a seasonal site, do it every time you dump the tank. Having a tank rinser makes it easy, but using the hand-held shower, using a hose and wand, or dumping in a bucket of water all work well if you don't allow the situation to get out of hand to begin with. Cleaning the tank until the water runs clear will also enable your tank sensor to give more accurate readings.
One last thing when dumping: it doesn't necessarily mean your tank is empty just because nothing more is coming out of your drain hose. Sometimes a plug will develop even if you use the "right" paper. I've found that opening and closing the gate valve several times quickly will often break up a plug and start the flow again. Putting your shoulder into the side of the trailer and rocking it will sometimes help, as well.
The important thing is you have to do some regular maintenance. You have to regularly check and maintain your tire pressures. You have to keep your wheel bearings packed. You have to inspect and re-caulk your roof seams. The toilet is no different! Use it! Clean it regularly! Maintain it properly, and it will give you years and years of odor-free service.