I've seen it used by men as a counter argument for being rejected. I've seen it used by women as an excuse as to why they man would cheat with someone lesser than.
As a counter argument? It kinda does work but not in the favor of the man saying it. We know that the longer we men go without sexual release the more built up our sexual impulses become to the point where you start finding less attractive women appealing. It's human biology.
So it's used as an attempt to put someone who is acting more attractive than they are after rejecting them in their place. It's an attempt to lower someone down to the level the rejectee believes the rejecter to be since in the rejectees mind if they reject them then they are acting as if they are above them.
It's dumb and people need to stop being so ashamed of their fetishes. You like fat women sometimes? So what. You like the way that ugly woman look when she smile with a missing tooth?so what. There are men right now jacking off to grannies, pregnant women etc. Being attractive just makes it easier to get who you want it doesnt guarantee you to anyone. As long as it is consensual, fukk whoever you want but don't be tryna put em down cuz they didnt want you