I am a woman working in operations.
Here is my opinion. It's just an opinion, but it's something.
I don't think work environments are singular entities that should be read as a whole. They consist of stories, experiences, individuals and the like. I apologize if this comes across as condescending. But I think you are feeding a personal bias or fear, and that you may limit yourself by thinking too broadly about the topic.
Think of your goal from the contrary. Even if during an interview, someone you are getting along with -- or someone you get "good vibes" from -- says exactly what you want to hear and you leave feeling awesome and respected, that cannot guarantee an absence of toxicity in the future.
So why even have a formal vetting process, I wonder? What more depth can you possibly get from a process like this? People come and go. People change. People make mistakes. People project their own insecurities. People have differing opinions and cultures. Unfortunately, that includes differing treatment of minorities in some cases.
I'm not trying to be a sympathizer to anyone who is bigoted, but human nature is unavoidable. Instead of trying to protect myself indefinitely (impossible, imo) I empower myself by reminding myself that I have a choice too.
If I'm uncomfortable or if I feel something is toxic to the extent that my personal life is going into shambles, I don't need to defend myself. I just make changes that are good for me. I'll turn down the job offer where I got 'bad vibes' or, if I'm already employed and going through discrimination that can't be solved by civil conversation or HR, I'll seek employment elsewhere -- I don't mean to imply jumping from job-to-job is easy, though. But if I'm really that miserable, it's probably worth it. Then -- I'll try to be wary of the things that made me miserable, and be mindful of them in future interviews/jobs, with the full expectation that things may change for better or worse.
It all comes down to compromise; and everyone has their limits.
I could use my own experiences to try and tell you how to read people or vet them but... it simply wouldn't be relevant to you as an individual. Ultimately, there are far too many subjective variables at play. If I rattle on and on about "red flags I learned from being sexually harassed", I'd be worried I'd give you irrelevant things to be biased about.
It sounds like you know which things you want to avoid. So I'd suggest to be candid, and initiate conversations such as "How does your team deal with discrimination? Have you ever had to deal with toxicity against a certain minority?" You have every right to want to discuss these things, but only YOU can determine what a 'non BS' answer is.
tl;dr ... YMMV. Be wary of personal biases. Try to be pragmatic, and maybe determine a list of "deal-breakers" for your workplace's social life / experience.
> I feel like I keep getting the same canned PR response of how great the culture is (for assumedly white dudes)
I am not sure what being white has to do with anything -- I find it a bit worrying that you're concerned about discrimination but are placing blame on one race and sex so easily. Don't play the same game you are expressing distaste for. That is not fair to yourself or anyone else.
Hopefully my perspective helps. Again sorry if this comes off as condescending, I mean the best, I'm just not super great with compassion in text. Good luck out there.