1. There are many reasons for odor in the bathroom. The more common ones are floor drains, toilets, sink drains, and ventilation fans. Therefore, we can deal with and investigate these aspects one by one.

2. We can first look at the toilet to see if it is clean. If it is not cleaned after use, there will be odor. Then we will check whether the toilet is leaking. If so, we can call a professional to repair it.

3. If there is no problem with the toilet, we can continue to look at the floor drain. Because the floor drain has not been cleaned for a long time, dirt may accumulate in the floor drain, causing odors to emit. We can just replace it with a new one.

4. The smell in the bathroom may also be caused by the pipes of the sink being leaking for a long time. At this time, we can open the sink and see if the pipes are leaking. If so, we can ask professionals to repair it.

5. Odor in the bathroom may also be due to lack of air flow. We can install an exhaust fan, if there is one we can check to see if there is a problem with the exhaust fan and it is not working.