I did a home inspection on a flipped home where they had a licensed master plumber but in a new bathroom. I hit them on the S-trap under the bathroom sink (first picture)Name:  P1010205 (Small).JPG
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Size:  27.7 KB. The agent asked to have the S-trap changed to a P trap. The second picture Name:  P1010190 (Small).JPG
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Size:  44.3 KB shows it is now an S trap with a vent. I also reported the vent stack is too short because it's below the drain flange.
By the way. They could have used a regular plumbing vent through the roof but they didn't.
Can somebody tell me if this plumber is all washed up?