I have the misfortune of knowing several "Polys" AND "Swingers" IRL, and "Trainwreck" doesn't begin to describe them.
Basically every one of them is the classic "One-Sided open relationship" thing where one partner (Pretty even split between male and female here, weirdly enough) is fucking everything in sight and using the other as a backup. And the other, usually an introvert, absolutely hates the poly thing, but stays because "It's better than being alone"
The difference is that polys claim it's because of love and the swingers say that since "It's just sex, it doesn't matter" Both seem like delusional sociopaths that don't give a shit about their "Primary" partner, IMO.
Also, there's recently been some sort of disgusting Chlamydia outbreak in the local poly/swinger community, and the drama is hilarious.