Odor in Master Bathroom
We have a puzzling odor in our master bath. The odor only occurs in the evening, and when it occurs it is almost always between 8:30 and 10:00 PM. We have never experienced the odor during the day and the odor does not appear to be related to our showering/bathing schedules, etc. The house is a single story on a concrete slab in AZ. The bath has two vanity sinks, a tub, separate shower, and stool. So far I have ensured all the traps are wet, I have sealed off all the drains and overflows with duct tape or left water in the sinks, I have checked the plumbing vent on the roof for obstruction, I have crawled into the attic to check for something dead. I have inspected my exhaust fan ducting to look for a birds nest, and I even sealed off the exhaust fan housing on the off-chance that my AC units may be creating a negative pressure in the house allowing sewer gas from the plumbing vent on the roof to sneak back through my exhaust vent. All of the above has been to no avail. Has anyone got any ideas that I have overlooked, or suggestions on resources to help find the culprit. I'm out of ideas, and my wife has moved into the guest bedroom.