Evil-smelling drains

Is the drain blocked or is it not draining properly? Does it smell too bad? Here I got a tip from a laundry service technician.

In my washing machine is the connection in the kitchen under the sink. There, of course, also accumulates fat in the drain from the dishes etc.

He advised me once a month to put 1 dishwasher pad on the drain. The same in the hand basin and in the bathtub / shower. Just put it on and over time it dissolves and degreases the drain. Nothing smells more and the drain stays clear.

In addition, I added a few days later 1 teaspoon of soda. For me it worked and for years there are no more problems.