Often times though the bathroom is always watered every time after use, but still the odor issue not only from the sinkhole, but also from every corner of the room.
This odor comes from the substance ammonia, which is caused by bacteria decomposing dead in the bathroom. Too often dispose of soapy water into the toilet line may be one cause. Wash the toilet with a special cleaning fluid for bacterial decomposition is not dead.
You can also try pouring the coffee into the toilet water to neutralize the odor.
The odor in the bathroom can also be caused by sanitary equipment whose quality is not good. For example, toilets that can accommodate large porous residual urine that is not doused with a tub, causing a bad odor. Choose a porcelain toilet with good quality materials to avoid the appearance of the odor in the bathroom.