I think understanding oneself and one’s circumstances can help here - as well as a sense of self preservation.
I know when I was a younger single parent in my 40s I dated a couple of total weirdos looking back, that I would never have looked at before. I think both men had subtle - not so subtle - nasty undertones. Though as they were mixed in with other things it was a bit confusing. Eg. really admiring an intellectual female actress - but also mentioning an interest in porn.
However having been single for 7 years I craved some male company, affection, sex, validation as a woman, potential as a couple, and potentially a father figure for my child. I was also probably naive and hopeful, and fooled myself, even though I was in my 40s and not inexperienced in life. Plus I felt this was the last chance to have a possible decent, stable relationship with a man, the kind of everyone else seem to manage but I hadn’t!
But as a single mother in her 40s, the pool of available men, and especially the opportunity to meet them, was vanishingly small. So there was a certain internal pressure to compromise or take risks that I otherwise wouldn’t have. In my case the restrictions of being a single parent made it harder to have a ‘see what happens’ lighter approach. Also, strangers you meet on the Internet (I don’t know if the OP met this man on the Internet) have an opportunity to present themselves in a certain way. And it can take some maturity and wisdom to see through the facade if you have not come across men like this before. It was a learning experience and it does make me shudder to think that I even entertained these two creeps. But there you are.
The OP may be in different circumstances to me but is asking questions and hopefully this will protect her from getting into a relationship with any such man.