When I drain my whirlpool tub I begin to smell this odor in my bedroom. The smell seems to begin in a corner of the bedroom and on the backside of the wall is the toliet. It does not happen everytime, it did it for 3 days in a row and then it was 5 days beofre it happened again. If I open the windows it is gone. Also by that corner is the drain clean out under the window. That side of the house outside stays wet from rain. This smell has been with us over a year and we have had 3 different plumbers out and they can't find anything. Does anyone have any good idea's? I have done the peppermint test and nothing from it. Many thanks!