I mean, I agree that there are varying levels of legitimacy, but that's kind of baked into the system at this point and it doesn't help that plenty of spammers don't have legitimate unsubscribe buttons and sell your email to a chain of ever less legitimate players.
> There's a clear distinction and I'm wondering if we'd have an easier time filtering out the actually bad stuff if people that think like you didn't muddle the data by marking normal email traffic as spam
Something tells me that you missed most of the history of dealing with spam, because people used to be naive about this back in the day and spammers exploited the hell out of them by using unsubscribe to confirm that the email was live and similar tricks.
Unwanted is unwanted. It really does vary by person, that much is true, but even your viagra spam is wanted by some people. But the people sending it are very often also doing a lot of shady stuff like running botnets, so the technical measures to stop that look very different from, say, looking up the SPF record for Paypal:
https://mxtoolbox.com/SuperTool.aspx?action=spf%3apaypal.com...
So the short answer is no, people not wanting to get spammed by Paypal isn't likely to get you more viagra ads from botnets. Maybe, just maybe, it could create some small headache for Sendgrid (who is in Paypal's SPF, but is no small player), but I doubt it.
That aside, I think a few of them frequent HN and they can answer that one for themselves if they want to.