Smell in master Bath/Bedroom

Hi,

We bought a ten year old very large bungalow two years ago. At some point in time after we moved in we began to notice a foul smell somewhere in the master bedroom and/or ensuite. The master bedroom has a large ensuite completed with double jacuzzi, sink, toilet and shower. You enter the bedroom via double french doors. The vent stack, enclosed in a jutout in the wall, is immediately to the left. Going further into the bedroom you turn left to enter the ensuite via an arched entrance without (obviously) a doorway. The double jacuzzi and sink plus powder room are separate from the bedroom with an arched entrance and thus no door. Once you enter the ensuite there is a door to the left that leads into the shower and toilet area.
It is difficult to localize the smell and I cannot describe it although it doesn't smell like faeces. We have cleaned the shower drain and sink drain rigourously several times, poured bleach into the toilet tank several times and although the smell may (or may not) be slightly lower, it is still there at times.

I always thought the smell was in the toilet and shower area but my husband has always complained about the smell as soon as he came into the bedroom. Most recently I am beginning to smell the same. He thinks it is most likely that the smell is coming from the vent stack and somenhow the vent stack was not connected or has a hole or something similar. He went into the attic and pulled on the pipe. He said he detected no movement.
I am now in agreement, given that the smell is strong when entering the bedroom and the vent stack is in the wall to the left, is it the vent stack and if so, short of cutting the wall what can we do? What are other possibilities that we have not investigated and how would we resolve them?
Is there a measuring device that could be used to determine where the smell is coming from and where it is strongest, etc. That would definitively help to localize it.

Thanks for any and all help.

The overflows from the sink or tub sometimes get crud in them, and you might try something like a bottle brush and some bleach to try cleaning them.

A shower that is not built right can start to smell like a swamp...doesn't mean it is leaking, but it seems many plumbers feel that a liner flat on the floor will allow the water to flow to the drain. If the liner is flat on the floor, the pan will fill up over the years with moisture that leaks through with nowhere to go...eventually, it smells pretty stale.

A vent stack would not be my first place to look for smells unless the windows are open and the stack is not properly located. I've heard of some people that actually had the plumber fail to extend the vent out the roof, and terminated it in the attic (illegal and very poor workmanship!).

If the vents are not done properly, it is possible that the trap(s) are being suctioned dry. If the trap for the shower or tub has a long runing arm, and not very close to the drain, this can accumulate hair and soap scum and smell nasty.

Vent goes out the attic - no problem there

How can I check to see if the traps are being suctioned dry? If that is the case, how can I resolve it?
We cleaned all the overflows to the sink, bathtub, etc. so that is not it. We have tried all of the easy things.
Relative to a long running arm, how can I check that? Again, I am beginning to almost think my husband is right about it being the vent just because when I come in the bedroom I can smell something and that is right where the vent stack goes up the wall. Again, I could be wrong.
Thanks for any and all thoughts and suggestions.

Typically, in a shower, the trap is directly below the drain. If you take a flashlight, you should see water in the pipe. If you can't see water and you can see the pipe turn, then the trap is not positioned properly or the trap is dry. If the trap is dry, it is not vented properly, and running water through one of the other fixtures suctioned it dry.

The toilet flange seal (wax ring typically) could be compromised. The toilet won't leak unless there's a backup, but it can leak sewer gasses. Does the toilet rock or move at all? If so, it needs to be reset with a new wax ring and shims to stabilize it.