Selective doses of being impolite can be extremely effective, especially when you're otherwise very polite.
(One of several variants: <https://quoteinvestigator.com/2015/01/21/offense/>)
The most effective method I've found is making that person responsible for resolving whatever the issue is. Not always possible, but especially when it happens in group settings, some verbal judo can work even if you can't "officially" task them.
(Make sure to memorialize that in an email afterwards, or it will probably retroactively never have happened.)
"So, I see your business model is to make widgets. But ... uh... I don't really understand these ideas but that's called capital intensive, right? So, you're gonna have a factory, with a bunch of workers... in San Francisco? Won't that be really expensive, and ... uh, I guess that means your profit margin will be small? Could you put your factory in Kansas?"
(paraphrased but essentially accurate question I asked when being pitched by a hardware startup at a major VC that I advised)
But more to the point, I find that asking for clarification is the best tactic in the aforementioned circumstances. That way, you avoid having to make accusations. It removes all pretext for getting defensive and focuses the discussion on the substance and merit rather than the character flaws and lack of speaking skills of the other. If the other person starts to get unjustifiably angry, this reflects poorly on them, not you, so there is no need to feel any guilt. Be honest and never lie. Do not pretend to understand someone just because you think asking for clarification will make you look less competent. Maybe you are less competent, in which case pretending to competence you don't actually have is dishonest and unjust. You also close off the doors to learning. And if you are competent, then there's nothing to worry about. Bullshitters feed off pretense, and honest people are dismayed by it.
The "reframe the conversation to the thing I want to talk about" - man, that one's frustrating. I don't have a polite way to stop that one yet. I think some of it is just that we all pick up traumas and trigger words, and you've gotta recognize when someone said "banana" that doesn't actually mean "the thing I slipped on five years ago."