Whenever we want to use the shower of the guest room, we see rising odor (shower Italian). What to do?
The siphon showers in the Italian being generally shallow, the water evaporates quickly. It no longer insulates the bung from the rest of the pipe.
We say then that the siphon is "defused".
To avoid this phenomenon, you just need to run a little water in the shower regularly (for example once or twice a week).
Be aware that the water guard (amount of water retained in a siphon) avoids the rise of odor.