When doing a house or apartment where any smoking was done it's been my experience that the smell will permeate every space. The visible staining may be more confined to a given room or area but the odor will be everywhere so you pretty much need to treat the entire place. Not having done so is likely why you still detect an odor.Because only one room has been affected by nicotine. Others are not. Just to save a few bucks.
Ahhh... you're right. Forgot this was about the BIN odor and not lingering smoke smells. usually it is the other way around.I think it's the odour from the BIN that's remaining.