(TL DR at the end)

What essentially is a red flag?

In dating scenarios, a red flag is a sign (not a symptom - they're actually different from each other) that a particular male would pose a serious risk to the overall wellbeing of a person forming a relationship with then. They're meant to be observed and taken notes of, and serve the purpose of a general warning.

It doesn't matter if they're observed before or after a relationship, as they will almost always persist (i.e. calling out on your partner won't do much to solve anything and may actually only make things worse).

That being said: I myself think we're being too harsh on most males which display some of these red flags and, personally speaking, believe most of them are really low-tier stuff, like lying to a partner or not being able to communicate efficiently. I'd happily ditch a male with a single of those red flags on their profiles but there's two issues here:

1) Since red flags are signs and those require senses and interpretation to be observed, they tend to be over/underestimated by women. This tends to reduce as far as our experiences grow, but it may actually never reach a 100%, sure-fire rate: We can always be wrong once, and there's no harm in that. Please note that this isn't a reccomendation to not ditch a male since no women needs a permit to get out of any relationship. It's a prerrogative. Ditch away :)

2) Red flags aren't intrinsic. Toxic masculinity, for example, isn't genetic, nor it's congenital: It's behavioral in nature, learned by men who grow up in such a society, and as such can be snuffed out with some effort before it does serious harm. This is fact and does not contradict any FDS principle: FDS simply points out that no women has any due or obligation to help a male deal with their own toxic behavior. We're free to stay away/cut relations with literally any male as we wish.

That being said, there is a "red flag" consistently unfit to the points above. The criminal record/ "RAP sheet of a male carries materiality of his acts and as such is the supreme indicator that a male is bad news, especially if they have any sort of domestic abuse in it.

I call it a black flag, and this is not necessarily brought or borrowed from pathetic incel lore (redpill/blackpill). They serve as the supreme, beyond any doubt that a male should be avoided at all costs by women. At all costs.

"Isn't this just legalism?"

No. A criminal record is proof that a person did X at time Y and this carries a lot of weight for those who examine. It's not something "open to interpretation".

And example that helps to illustrate this: A popular red flag is a (often inexplicably) refusal to commit to a relationship, especially on On-line Dating (the worst kind of dating, btw). It is treated as such because it is difficult or downright impossible to ascertain the reason why a man won't commit - it could range from st\pid personal insecurities to the guy actually actively* roaching you! Since you can't be sure of the true reason, you'll consider and eventually decide if the risk is/isn't worth taking (i.e. A male who is attractive, fucks incredibly, is great in almost all other fields, but won't commit nonetheless).

(Remember: Leaving relationships is our prerrogative, but not mandatory. I'm not telling anyone what to do.)

With a criminal record register, there is no room for a reasonable doubt anymore. There is no risk assessment anymore, only the certainty that he can and will perpetrate specific (or worse) acts against you given the opportunity and conditions. This presents a tangible, real danger to your wellbeing and, possibly, your life. It's no longer a case for "if" but for "when". Applying this to the same example above: being "near perfect" in every other aspect would not save a male's value if he is proven capable of harming/assaulting/abusing women.

As such, it takes maximum weight when assessing the value of any particular male. Background checks saves lives.

Oh, and obviously this also applies to any act a male perpetrates against you or people next to you that would enter their criminal record if investigated and confirmed by authorities (i.e. acts of domestice abuse on camera)

-----

TL DR: A criminal record is the supreme red flag ("black flag") due to materiality and an above-doubt indication that a male should be avoided at all costs.