I think it's impossible not to have some standards. Even if you consciously think you don't, and THINK you are pursuing all possible candidates, subconsciously you probably have some (even if they are very simple/low) and are inhibiting putting maximal effort towards the most achievable candidates.
No particular standard stands out as more/less acceptable than others. Ultimately it is about what % of the population you exclude, and how those %s compare to other men's standards of exclusion.
We have little sympathy to the lack of accomplishment of someone whose standards are so exclusive as "I will only fuck this one particular movie starlet, nobody else" for example, and more sympathy for say "I want to have sex with a biological female who is less than 60 years old and who does not have STDs and who is not addicted to crack-cocaine or heroine".
Ultimately though, even the latter is still some form of standard (and seriously, do we think more than 10% of "incels" would accept that if pursued, much less go out of their way to pursue it themselves?) which is a voluntary thing...
Unless of course we declare all standards to be involuntary (we can't choose what disgusts us or gets us horny) in which case we must then ask: what IS voluntary?
I think a lot of people here are average looking standardcels who underrate females on purpose so they can then say above-average females are actually their looksmatch--which they're entitled to, of course. (Not.) Genuinely average looking females get mocked on incel forums for being ugly landwhales all the time and I'm fairly certain that kind of person is who's behind it.
Examples please. This is too subjective. We must put together a study.