Well on my "for you" page, I also follow a pretty niche audience of tech people, which helps :P They're a little easier to verify since they generally also have blogs, or websites, or github accounts, or youtube videos, etc that help verify they're not bots.
I also think people create bots for some purpose -- instability, political divisiveness, financial gain, etc. And I'm kind of inherently not using twitter for any of that. I don't think I could find an account on my twitter thread that mentions the word "liberal", "trump", "conservative", or any of that if I tried! I agree that's a muuuuch more likely place to find bots. What sort of bots do you notice the most in your twitter?
Yeah I suppose if you are already vetting based on identity from outside the network that probably does scale. Most people aren't as careful about this as you are, though, so it'll still be a problem and it will have to get much worse before it gets better.
I'm not on twitter. I left when the tidal wave of right-wing spam started to outweigh the entertainment value of seeing Yann LeCun dunk on Elon Musk.
I have a theory, which accounts like yours would be very interesting for.
Instead of looking at it as a per user basis, if you look at it as a network or ecosystem, the issue is that the network is being flooded with spam.
Since nothing happens all at once, over time different filters will get overwhelmed and eventually impact the less networked accounts.
It would be VERY interesting to find out when, or if ever, you begin to suspect some accounts you follow.