It pains me that this requires explanation.
A couple (of any genders) seeks a person (of any gender) for a casual threesome.
Totally ethical.
However, most couples who do this are gross. Its often a m/f couple seeking a bi woman to fulfill their fantasies without regard to hers or her desires. Which makes it gross because this a gross way to treat casual sex partners (gender is irrelevant), but not because having a threesome, foursome, orgy or casual sex is morally or ethically wrong. However, It does give these folks a bad reputation for good reason. Especially since they repeatedly pursue and harrass bisexual women with no interest in threesomes instead of pursuing enthusiastic partners. . But that doesn't make threesomes inherently wrong. Sex isn't inherently wrong or bad.
Polyamory is an agreement that people in a relationship can have other romantic and sexual partners. Polyamory is ethical, but being in a polyamorous relationship doesn't make everything those people do ethical. You can be polyamorous and treat your partners or potential partners in an unethical way. Just like monogamy is ethical, but some people in monogamous relationships are toxic and abusive.
Polyamory unicorn hunting is when an established couple (of any genders) seeks a serious romantic partner (of any gender) to have a triad with them, but requires that person to always fuck and love both of them. They almost always expect it to be closed as well.
For example:
Bob and Steve are married. They decide to do polyamory, but will only date together for a triad.
They meet Tom and expect Tom to date and fuck them both. It doesn't matter how they meet or who approaches who. But if Tom only falls in love with Bob, then both Bob amd Steve dump him.
However if Bob doesn't fall in love with Tom but Steve does...well....they still both dump Tom.
Because they prioritize the structure of a triad that always protects their original relationship over their new relationship with Tom. Tom will never be as important as the relationship they have with each other.
Bob and Steve will always dump Tom if the threeway connection fizzles. Bob and Steve will always prioritize their relationship with each other.
Tom is always disposable.
People seeking to treat someone this awful way while seeking a partner for a polyamorous triad always say the same thing. They defend their willingness to abuse and dehumanize their partner by saying
"It's not JUST about sex. We want a REAL relationship. We want to LOVE this person. Its not JUST a sex hookup".
As if sex only relationships are inherently unethical, but as long as theirs is more than sex, then nothing can be abusive, toxic or unethical.
...............
Thinking that making something only about sex is dehumanizing while thinking that asking someone to offer you their heart and then treating them poorly is not dehumanizing because its about "more than sex" is fucked up. Because the opposite is true.
Just because you are offering love, it doesn't mean you can't also be abusive. Love isn't an absolution for unethical behavior.
Just because something is about consensual casual sex, doesn't make it wrong. Casual sex isn't inherently unethical.*
*Although people are frequently unkind to their casual sex partners which is why there are glut of couples seeking threesomes and very few singles interested.
Thank you!!! Good summary. I get people regularly insisting that casual sex = using people and "oh but loving them makes it ok" and you've summarized the distinction of that bullshit perfectly.
Hell even though people DO mess it up, casual sex has so few moving parts (lol) compared to a full ass relationship.
Very hard to isolate someone and mess up their finances during an hour of casual sex.
Very hard to break someone's heart unless you are VERY BAD at listening, sex, or both