What's a tell tale sign someone doesn't like women?

They clearly have a negative stereotype of women in their minds, and that's the lens through which they judge the behavior of all women. So if a woman forgets something, it's because "women are airheads". If a woman is upset about something, it's because "women can't control their emotions". And if a woman is good with kids, it's because "women like children, that's just natural".
And when a woman behaves counter to his preconceived ideas, she's a bitch.
- This is a good one! It says a lot

When all examples they ever give for anything consist completely of men.
Have you ever looked into a reddit post on a topic like "Who are the best actors of all time?" Thousands of comments, nearly all male actors. "Worst actors?" Also all men. "Examples of this trope?" Only scenes with men. Stock photos or drawn figures to illustrate their point? You guessed it – all men (unless it's sexist in another way).
For some men we just don't exist as people of equal significance.
- Yeah, a "men are the rule, women are the exception" mindset really tells a lot.
- Indeed, when I started at my current job there was a Anglophile guy who was really into the Beatles and other "classic rock" groups. Being from an English speaking country he was keen to talk to me, at length, about music.
  After a while I noticed that he never mentioned any groups that even had one woman in the lineup, I started asking his opinion about the likes of Janis Joplin and Heart, and he just kind of locked up.
  He will now say a frosty hello to me if I prompt him directly, but that's about it ... he has two daughters who don't talk to him apparently.
  
  Lol
- I've started seeing a few more comics/memes which have women as the representative of a universal experience (rather than, as you say, representing a sexist trope) and it's absurd how happy it makes me.
- This might be a bit pedantic, but if they're asking about "actors" that usually implies they're asking about males. So if you're seeing only male actors in response that's probably not so much sexism and just people just responding accurately to the question being posed.
  If they phrased the question as "Who are the best actors/actresses of all time" and people still only came up with male actors then okay yeah.
  
  I did not mean to make it seem like I was quoting a specific question word for word, it was more about the general concept, however it is worded. It might be worded as you put it or not be about actors. Or like my example be more generally about movie scenes. Or...
  Unlike my native language, English is usually ungendered and I sometimes forget that there are some few exceptions to that rule.

Refers to women as females
- That's a good one! Immediate red flag

Bitterness in the tone, even if it's just for a second. Maybe a slight eyebrow raise or almost eye roll as well.
No patience with women having trouble with driving, DIY or other things women are more likely to struggle with.
Often makes disparaging remarks about famous women, for example tears apart a politicians views or ridicules a female performer. Doesn't seem to do that with men.
- Wait, are we more likely to struggle with driving? lol
  
  Haha should have said we're believed to struggle with driving
  
  That is a stereotype. Might some of that be due to the fact that driver's seats are designed with men in mind, and tailored to the average male body? Maybe.
  Also it's worth noting that men are more likely to be involved in fatal accidents than women.
  
  I mean, I'm a pretty terrible driver but it's not like my uterus is doing the steering!

Here in the South a telltale sign seems to be when they talk shit about their wife with their friends, it's like a point of commiseration that seems to generalize to misogyny, the whole "women, eh?".

You can usually tell when a man doesn’t like women by how he talks about relationships. On places like AskReddit, you’ll see guys who feel entitled to sex or affection because they’ve had a hard time dating—and they blame women for it.
They start to resent women and expect them to take on traditional roles like cooking, cleaning, raising kids, and working full-time, all while splitting the bills.
Their idea of a relationship becomes purely transactional—like a checklist—without any genuine care or respect for the woman as a person.
- Transactional is a good way of putting it! Their expectations for women are high (unpaid housemaid and nanny, attractive etc) and they think their necessary "payment" is minor. You see a lot of entitlement, and then resentment. Then of course it's our fault!
  
  Sadly yes. Shoot, you'll even have some women paying for those guys credit debt, all his bills because he's 'in between jobs'... and does nothing but play Xbox all day.
  I could go on, but I'll spare everyone lol

Hates feminists. Shits on female celebs and drama around them but not male. Brings up how dumb all the women their age are a lot. Watches certain youtubers that are right-wing manosphere types. Common bs like men are logical, women are emotional, praises men for sleeping around but scolds women for the same, etc. Mention the gender pay gap and they say men do dangerous jobs while women only do cushy jobs as an explanation. Is a conservative religious type or says they are in the center / don't like politics but when you mention an issue about women it is brainworms galore. If two women appear to take the same sides in an argument, it is only because they are both women. Talks shit/complains about women in a generalizing way.
- Ha! This is so true. I'd not thought of the "only siding with each other cos they're women" it's bang on the money

Every ex-girlfriend is "crazy."
To be fair, off meds at the time, I am actually someone's crazy ex.
- Haha hear you there! The odd one is fine though it's not a pattern

When they refer to women as "females", especially in the context of referring to men as just "men" in the same sentence.

Talking over women, repeating what they say, as if they said it, to give it "authority", not asking questions, but just making statements, "correcting" women after they speak, either rephrasing it, or correcting minor grammar or pronunciation, (that's questionable to correct, usually nit picky and way too formal for anyone to actually use, nowadays) while completely detracting from, avoiding or distracting from the point she's making. Minimising any mentions of struggles she mentions or people in general mention, that women face, especially if men are the cause. Anyone who says not all men, or bullies someone into saying it, double points if they just focus on not all men-ing and don't even mention the original point the op was making. I could go on.
- Making "statements" is so true, and particularly annoying when you're the one who knows the subject best!

They only catch male pokemon /j

- Hey LMDNW it's good to see you here! There's no politics here so I've had to edit your post 😊