Although I have read much information re: smelly sewer smells in bathrooms and how to correct, I haven't been able to figure out the source/solution for the very strong soapy/sweet detergent like smell in my master bedroom ensuite. My house is just two years old and we noticed this after living there for only a few months. The builder will not send a plumber, saying it just smells like a bathroom but it is much stronger than that, even after taking out all bathroom products out of the room. On two occasions for 2 weeks to a month we did not use the sink, shower or sink faucets; did not flush the toilet;and opened the window every day. Only then did the odor dissipate somewhat but within a day of using the washroom the odor returned. We do not have this smell in the other bathrooms nor have we encountered this in other homes with smaller, poorer ventilated bathrooms. We have cleaned the drains but this does not help. I wonder if the smell is somewhat musty and something is leaking but we can't see it. Any ideas out there? Thanks.

It might be that your drier vent is not ventilating correctly from under your house.

I lived in a house one time that had a hole in the ventilation ductwork under the house - & it made a sweet smell in our bedroom from the laundry detergent & it did smell a little musty because of the clothes being wet. I don't know - that was just my first thought when I read you post. Good Luck!

Its possible you might have some spilled detergent somewhere or another causing the smell. Charlie has a good possibility too. Dryer lint does have that sort of smell.
It could also be a minor leak that has caused some rott/mold build up in some corners of the bathroom.

I have the SAME problem with the soapy/detergent smell, and I swear it is somehow coming up from the septic pipes. The smell is in my kitchen. Venting is fine, no plumbing leaks, so I KNOW it is SOMETHING to do with the Septic. The smell is driving me NUTS.