How do you identify a problematic recruiter, a recruiting process, or an offer early?

I have had a few competing job offers for highly technical remote roles. The recruiter in the earliest offer was seemingly personable at first during the initial screening call. The process moved a little slow and when the recruiter's client sent a calendar invite for the call to technically vet me, the job title was wrong from the role discussed in the screening call. I sent the recruiter an email asking if this was correct and if she had time for a call to discuss. Her response was, "I am positively swamped today with other calls, but what can I do for you?" I thought I was misreading tone, so I let it slide.

I went through the technical vetting and talked with the company's C-level. Excellent feedback from them, the C-level told me so personally and even asked 'where I had been hiding from them' all this time. So we reached the offer stage--I had established a mutually-agreeable anchor compensation value with the recruiter in the initial screening call--I don't want to waste their time or mine. They low-balled the offer the worst I have been low-balled in my career. Again, I was lenient in consideration. I had other offers, but I didn't mention those yet. I asked them to consider the earlier conversation, my fit to the role, my years of experience, etc. They came up halfway to the previously agreed anchor. So I informed them I had other offers for quite a bit more than my anchor value, but I was just seeking my anchor.

I received another call within minutes, the recruiter made a comment about someone in C-level asking if she thought my competing offers were bullshit. I didn't care for that, but once again I let it slide. I wanted to ask if she thought their offer was bullshit but I refrained. While on that call, I quickly sent the recruiter some selective screenshots with just enough detail to verify my assertions. I shouldn't have even went that far. I didn't hear from them for another day, so I sent an email withdrawing my application and thanking them for their consideration. This was not a negotiation tactic, I planned to take another offer.

The following day, I received a call from the recruiter indicating they were agreeable with exactly my initial ask and a vague description of shares in the company. I asked for basic specifics, grants, options, etc. She had no idea. I was interested that they met my asking, but also wanted to explore the potential of their shares. So she scheduled a time for me to talk with their CFO--I heard the specifics from him as if the ESOP had been implemented. They put it in writing in the offer and it was just a big IF--the ESOP itself had not been implemented and was still subject to board approval. I told them I wanted the weekend to consider.

I reached the decision to back away from that startup altogether. I don't want to hear anything else out of them. I have ghosted them, and I feel bad for that. That was the worst recruitment process I have ever been through, and the recruiter is a complete hyena. She has sent multiple messages today telling me how disappointed everyone at that company is in me, and guilt-tripping me that it would 'at least be nice to know why'.

TL;DR: I was put through the wringer. Don't be like me. Hopefully you have some sense for early identification with problematic recruitment/hiring that I don't. Please do tell so that I can better identify these situations in the future.