The second bathroom in my house has a foul smell coming from the toilet, and if not flushed for 24 hrs, starts to develop a yellowish/brown film in the bowl. I pulled up the toilet, and replaced the wax ring ( which looked fine and had no dampness around ) but this did nothing. It is used frequently, and one day it just started. Bleaching the tank and bowl helps for about half a day, then the odor starts creeping back. Not sure what else to do here...i have some basic plumbing skills, but this has beaten me.....the pipes from the house to the city line were just replaced due to tree root damage, we thought that would help also....but nothing. I have been told there may be an issue with a vent pipe???? but i do not know if that could be an issue, or if it would cause this type of problem in the bowl itself.....??? Any help would be greatly appreciated!!! The daily routine of bleaching is getting really old !!