Re: All of them.
Salo really isn't that bad. There's some sex at earlier points in the film, but nothing graphic or particularly horrifying. The $hit-eating is icky but they don't dwell on it that much. they save all the graphic deaths for the end, and they're explicit but happen very quickly. I don't think the movie comes anywhere near the gore-fest horror stuff of contemporary times... it's more the concept and notoriety that keeps it being mentioned still. I haven't seen Serbian Film and don't really plan to, but it couldn't possibly compare to Salo (in terms of how gross it is or artistic approach).
I haven't seen Come And See in 10 years, and it's not really graphic or anything, but I was kind of battered by it and sort of begging for it to be over toward the end... but I would still recommend it. Salo, I would only recommend for the film buffs... I don't think it's like this "gag reflex totem pole" movie like Cannibal Holocaust or something... people should watch it more so if they're actually interested in Pasolini, hah!