Well, it may not actually stink, but sometimes there are odors in our homes that are difficult to track down the source. Let's explore some possible causes:
1. Sink and tub/shower drains all usually have a "p trap" or "s trap" that is there to prevent sewer gas smells from entering the house. However, sometimes there is a drain in our homes that may not get used all that frequently. In this case, sometimes the trap can have all the water evaporate from the drain, and the result will be sewer gas smells entering the house. The simple cure for this is usually to just run some water in those drains that do not get used so the trap gets replenished with water, thus stopping the gas smell.
2. Sometimes, a toilet may be slightly loose from the floor, which will cause the wax ring seal around the drain hole under the toilet to become unsealed, which will also allow those sewer gasses to escape into the house from around the base of the toilet. The solution here is not quite as simple; the toilet must be removed from the floor, and reset with a new wax ring, and then securely tightened to the floor.
3. Bath fans sometimes do not get vented to outside as they are supposed to. Many times they are terminated in an attic space, which can lead to stale air being recycled back into the house living space. All bath fans, (and dryer vents) should be vented directly to an outside location.
4. Sump pumps that are unsealed can sometimes bring stagnant or otherwise smelly air into the house from the piping from around the footer drains. (You never know if there is stagnant water somewhere in the line, or sometimes just the earth around the pipe will have a bad odor that can be transmitted into the house through the lines). If this condition occurs, it is probably best to have a sealabe crock lid installed on the sump pump.