I don't read too many manga but probably the most tasteless scene in a manga would be a scene of....
-a naked Goku scratching his groin in public. (Dragon Ball manga )
-Saori Shikijo-sensei indulging her fantasies about younger boys (Mahoromatic manga)
-Shiina Yuya lifting an old lady to block Benitora's lips. (Samurai Deeper Kyo manga)
- Ryang Jegal accidentally slapping his bare (uncovered) hand on a cockroach while the many layers of tissue slipped off his hand. (Faeries' Landing manwha)
But no scene in any Japanese manga or korean manwha is too tasteless compared to the scenes in Pugad Baboy (philippine comics).
This guy who was sniffing the drug dealer's armpit in order to inhale the drug embedded in the armpit.
A dog-like person called Polgas fainted out cold taking a whiff of that guy's smelly armpit.
