Odor from bathroom when windows open

[Jaden Ghylin]

I own a property with a weird problem. There is no odor present in the house if the windows are closed. However, if the windows in the master bathroom are opened and there is a slight breeze, there will sometimes be an odor present coming from the toilet room(Separate area of the bathroom for the toilet). The odor seems to originate from the toilet room and it seems to smell like a sewer gas type of odor, although I don't have much experience with odors, so I could be wrong. The vent pipe is well above the roof line about 20 feet up, so I don't think it's coming in the window. The toilet has been replaced and resealed numerous times with no effect. All of the traps in the bathroom have water in them. I even had a company come out and pump smoke into the main sewer cleanout in the basement to see if the smoke came out of a wall somewhere, but it didn't. They were convinced that there is no leak in the plumbing system or vents, but I'm not sure it totally convinced me.

Any ideas on what could be causing this? All I can think is there is a leak in the plumbing vent from the toilet, but I really hate to rip the wall open to find out that isn't the problem. This has been going on for over a year, so I don't think it's a dead animal in a wall either.

Thoughts? My next step is to rip the wall open unless I get any other ideas.

Thanks,
-Jaden