Also, I think dating sites are a bit "a market for lemons".
Put more concretely, because different people have different dating preferences, one person's lemon can be another person's peach.
In addition, a market for lemons usually requires a seller to be able to determine the value of goods while the buyer can't. On dating sites, both the user and the site itself are trying to "sell" that person to prospective matches. Neither of those parties has all that much better of a way to determine a person's match-ability, so there's not all that much asymmetry. I suppose the site does know a little more based on history, but I don't think that's necessarily enough.
I do think dating sites are pretty garbage, but I don't think it's due to the phenomenon described by "a market for lemons", but rather due to multiple other factors.
WRT. lemons, I was thinking primarily about the aspect that the most desirable people disappear from these sites first. Sure people have different dating preferences, but they're correlated, not uniformly random. I believe that, while there may not be a total order of people that's the same for everyone, there is some rough order that would be acceptable to most, and the closer to "best" end in that order a person is, the shorter they're likely to stay on a dating site.
That's a nice way of looking at the world, and of course it's true sometimes.
But...hasn't all the data coming out of dating sites kind of proved the opposite? Especially for men, something like the top 10-20% are getting basically all the matches and messages.
Well, the person posting their height/weight/photo knows whether it's accurate or not, whereas the person reading it doesn't; that's your asymmetry right there.
Are you saying that short people should lie about their height and hope they can convince someone who's met them to change their affectational preference? "Conversion therapy" doesn't work. If someone is only attracted to tall people, you can't change them.