You cannot claim true motives are unknown if you claim the character is not a bad guy. If Orochimaru's motives are unknown, then his status of hero, villain, or anti-hero are unknown. The fact that Orochimaru broke off his pod and is sneaking around is very suspicious as is the fact that Kishimoto purposely cut us off before Orochimaru gave his reasons to Sasuke.
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Itachi died for the village but it was not the ideal village. Sasuke clearly states there that he plans on making "a true village" so this keeps in line with some of Itachi's dream but with Sasuke's usual twisted logic. You can tell Sasuke is not like Itachi since Itachi would not have attempted to carelessly kill the tailed beasts like Sasuke did.