My ex's OW, now wife is like 40 lbs heavier than me, older than hth of us and just straight up unattractive. They usually " affair down"
My W's OM has a beer gut, pasty white complexion and radar ears that are HUGE and stick straight out from his head. He's a nice guy, but he is such a goober it's unbelievable. Not to toot my own horn (OK, maybe a little, LOL!) but I'm in the shape of my life- washboard abs, beefy pecs, shapely arms, nice tan, etc. And dammit, I'm a super-nice guy too, a hard worker and have a great-paying job! Like you said, OP is almost always a step down, it's one of the mysteries of WAS affairs. Seems that the only selling point that really matters to a WAS is that the new OP is not the LBS.