This is something you'd have to be very careful about, since players would likely get very annoyed if too many NPC 'hints' were outright misleading. The ones you mentioned seem fine (since they're basically just 'generally right, but missing some info'), but the tendency of NPCs to lie outright was one reason why Castlevania 2 got so much flack back in the day (along with a shoddy translation that made it even worse).

Can work well for a puzzle though. Recall a few Zelda games having setups where one NPC was actually a spy for a rival group, and you needed to cross examine what other NPCs said to figure out who that was.