Barb's "illiterate" has it's own entry, so that's legit target (even if completely stupid).
Druid's "weapon and armor proficiency" is targetable, and easily replaced.
Collides with the basic fluff of the class.
Paladin's "code of conduct" might be targetable, I'm not sure.
If so, that would eliminate all sorts of insane-al-retentive bad player modes.
Perhaps the SRD is not the best source for the specific details on this one.