Improper shower drain installed at factory

[John]

My RV tech just spent 3 hours changing 90 degree elbow drain on shower which was allowing sewer gas to backdraft in swapped out to proper p trap
Should have been a 15 minute the threaded coupler was cross threaded on ab over tightened making for a very difficult swap.
Sheesh man quality control before trailer leaves factory ? I didnt trace this issue till warranty was off trailer.

 

[KCAlis]

Assuming you changed out a mechanical, “waterless” p-trap for a traditional one. Was there anything special about the p-trap the RV tech used?