A good way to get rid of stinky and smelly drains in your home is to use baking soda and vinegar.
Dump a cup full of baking soda down the stinky or smelly drain and then let the baking soda sit for 15 minutes in the drain.
The baking soda will help to absorb the odors in your drain.
Then after you let the baking soda sit in the drain for 15 minutes you take 1/2 cup of white vinegar and pour it down the drain.
Then you should see some bubbles and hear fizzing and you should let it sit for another 15 minutes.
After that time you take some boiling hot water and flush the drains using boiling hot water which will then get rid of the baking soda and vinegar and get rid of the smelly drain.