I can second that. I'm a liberal (well, sort of - more like strongly left-leaning libertarian), but I'm also [sanely] pro-gun, and so I am, or was, a member of various corresponding organizations. It appears that they share member lists, because I'm also getting a bunch of Republican political spam, both email and snail mail.

And yes, it is definitely much more nutty than anything I've ever got from being a member of ACLU, or subscribing to various Dem mailing lists in this cycle. Your description is spot-on - left-wing political spam tends to be click-baity and appeal to emotion, while right-wing one is chock full of debunked conspiracy theories and blatant fear-mongering.