Pasolini reaches an innumerable amount of rich metaphors surrounding fascism. The final scene contains the most powerful one, in which the villains take turns to watch the obscenity they have staged, reaching their final pleasure only by the safety of being separated by a window, as if ejecting themselves of the production of violence, hypocritically consuming it as mere theater, attenuating its severity.
Pasolini's last work is a must-see to every youngs out there, to realise the importance of rights as human beings and what can mean to lose our freedom in the hands of a few persons. Salo showed through Sade's main work, becomes a place without dignity for life, where death becomes the unique salvation. Important to watch.
All throughout is this undercurrent of looming impotence; these half-flaccid old men in their world of dilapidated opulence, so clearly desperate - despite their apparent power - for a way to keep it up... The dynamic isn't unfamiliar. For us so sure we'd never collaborate: Don't we, though? And aren't we sadist, and victim? Truths as distasteful as what's on the screen. Bonus: Watching fascists eat (literal) shit.
In the case of Salo, I think it's enough to watch 15-30 minutes of it to get the point. It's more about the concept than actually having to witness it all. Watching the whole thing make you complicit in what's going on. There is no great underlying message in this. I suppose the only redeeming factor would be that everyone enjoyed making it.