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.
In a way i was always punching above my weight with my W. She is a 8.5 or a 9 on a good day. I'm 7-8. OM is maybe 5 with a paper bag over his head.
M36 W31 S4 S2 T5 M4 BD Jan12 S July12 Recon Sep12-Nov12 ILBINILWY Jan13 OM x 2 in 2013 W wants R July 13 I start D. Jan 14. Meet GF Nov 13 Have I changed enough? Jul 14
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. 
