Sometimes a plumbing trap the is void of water will allow fowl odors to pass into the room in which they are in. Sometimes the water will contain minerals such as sulfur that can give off a fowl aroma. At a point in time my first wife mistakingly fed our dog cat food over a short period of time that produced a chemical reaction that should never have happened.

Fowl odors? Avian related?

Okay smarty pants, "foul"

But thank you for pointing out my faux pas. I am blaming it on the Heitz Cellars Cabernet Sauvignon 2015.

When we were looking to buy our previous house we noticed a slight smell in the master bath. We flagged it during inspection. Turned out the wax ring in the toilet had deteriorated and was letting sewer gases seep through. Easily fixed, but surprised they were living with it and didn't notice.

We are now in a neighborhood that uses well water for irrigation. Each property has their own. Most of them smell of sulfur and sometimes worse! Luckily most people run the sprinklers at night so you don't smell it that often. A few of the wells also have iron which stains everything. We went really deep with our well to avoid the iron, but the sulfur smell is still there!

In a new house that wasn't lived in yet, my first guess would be a plumbing issue, like a dry trap, or worse, a missing vent.

Why didn't you ask the builder?

If you've got a problem with an odor, you owe it to yourself to seek out the advice of austin air companie. Ray Austin has forgotten more about stink than most people will ever know. Heck, his nose knows about every kind of smell there is--- even rarely occurring conditions like dirty sock syndrome. I'm betting he'll nose what to do.

@Charles Ross Homes Nicely done.