Bad Toilet odor

If your sure it's from the toilet then go to any RV store and get some toilet chemicals. They work.
All this talk about not needing them is fine until you really do.

I determined that my black tank never really fully empties. Our last trip was without a sewer hookup as none were available, so I wasn't able to flush the system at the site. I had to dump at the campground. At home while cleaning I noticed it was still pretty smelly, and a look down the hole confirmed the reason for that. I filled two gallon water jugs and headed to a Pilot and dumped there. Must have been a hang-up, as the extra dump seemed to help. In the future I will always load some water jugs first if I need to dump and won't hooked to sewer.

If you have any sinks, showers, washing machine drain, etc that you do not use, make sure the p-traps have water in them.

jim behr wrote:
The past month we have experienced a bad oder from the toilet when flushed...

Is it only when flushing? If so, nothing is wrong, __it stinks. When you flush the toilet, it is open all the way to the tank. There is no trap like in a house toilet.

Make sure you aren't running an exhaust fan when flushing.

Also your vent pipe could be blocked. Run a hose down through the vent pipe from the roof with water running. If that's it the smell will go away.

I would go with gray water tank if everything is normal. Grease and other things like to stay in the tank and rot, if not flushed adequately and even then.
You're not leaving power vents open, I assume.
We use chemicals to control possibility of stink.
When parked, we sometimes leave the gray water open when washing clothes and there can be quite a bit ,of pressure back up into tanks, we've discovered, in some RV Parks. The ones that don't have field lines septic systems, just tanks, that have to be pumped usually. Our gray water smells like like liquid/gel bath soap and shampoo or laundry soap/bleach. Most of the time, after washing clothes and any time we leave the coach we close the tank valve, not only scents but critters like slugs, we discovered in Mississippi.
Put detergent and water softener into the tanks, partially full. Next trip down the road should/may clear out any deposits when you drain and flush the tanks if that is the problem.

Do you have any fan running? Whenever we have one running, whether it's from the A/C or the ceiling exhaust fan....there is terrible odor when flushing.

Check the batteries for proper water/electrolyte level. People have been fooled by the nasty smell of low water in the batteries.

Probably the grey tank - replace the air admittance valves. We had to and the odors all disappeared. They do wear out.

I'd suggest filling the tank full via normal usage...maybe use more water than usual. Then dump, repeat and see if smell persists. Maybe something got hung up and is above the water line.