I'd put this firmly under the "juvenile tendency" category.
I dunno. There's a stark difference between Mr. Blonde (a character everyone acknowledges as a sociopath) and the pawn shop dudes who are clearly sadistic with Jules and Vincent who has the audience sympathy. With Marvin, we (the audience) are left with rooting for "the good guys" to effectively erase a human being off the planet, as a joke, and Marvin is someone who we, the audience, have no reason to see as deserving of such a fate. All we know is that he's the inside guy for Marcellus. It's different when the film presents clearly sadistic characters doing sadistic things, but the dehumanization of a random person, being cheered on by the audience for no reason, goes a lot further to normalize the indifference of human life. And anyway I still don't see that being the case in Django, where the dehumanizing acts are exclusively committed by those who will receive their cathartic comeuppance.
Tomato, tomato. Anyway, I appreciate the fact that other characters admit that Blonde is a psycho, but still, when you look at Tarantino's subsequent films, his actions aren't any anomaly, but a preview of the general tone of QT's career (save for
Jackie Brown, which is the true outlier as far as that goes), and, although the cop in
Dogs is obviously a much more minor character in that film than Butch and Marcellus were in PF, I still felt sympathy for both of them as they were being tortured. As for Jules & Vincent's disposal of Marvin, I agree with you that it's a sadistic sub-plot, but it's not an either/or dilemma, as it's possible to find the tones of
Pulp &
Django both sadistic in their own way; the difference between them is, while the sadism is an obnoxious tendency with the former, it still has the theme of redemption running through it, which is explicitly delivered through one of the greatest monologues every written/performed in cinema history, while the latter has almost nothing of the sort.
And at least with
Dogs, there was a sort of honesty about the nihilistic, empty nature of its sadism; with some of his historical revenge films, it just feels like he's dressing that up by appropriating the struggle of certain historically persecuted groups, by having them engage in these hollow revenge fantasies against their tormentors, which naturally results in some incredibly obvious, softball choices of villains, as if Tarantino's saying "Hey, you gotta be engaged in watching these people get their vengeance against their persecutors; I mean, c'mon, they're literally
Nazis &
slavemasters!". It all feels like a substitute for getting us invested in their stories a proper way, which is by actually developing his characters in compelling manners, as opposed to just using them as avatars of revenge, as far as I'm concerned.