I guess I don't like Bluff & Insight as skills at all, really. Judging the truthiness of an NPC - as played by the DM - should be up to the judgement of the players, not the dice. (BTW I don't know why it's supposedly ok to give players an abstact puzzle to solve - riddles etc - but not to expect them to judge human interaction with their own judgement).
But I don't see a problem with players asking 'do I think he's telling the truth?' and getting a roll on request. That models the PC assessing body language and other non-verbal stuff the DM may not be representing. If they are suspicious of everyone, fine. Their PC will come across that way in play.
I don't give people active Insight checks unless they're interacting with the NPC, but I'll let them use passive perception if they're just watching.
Like I said, I'm not happy with the Insight skill, nor with the concept of the Bluff skill. I don't find they work well in play. Maybe in groups where nobody ever speaks in character, you just roll dice, it'd work.
Edit: Even then I don't like abilities like Bluff where you want to actively avoid using it! Because AFAICT there are no rules for assessing the truthfulness of someone who *is* telling the truth, it's apparently left entirely to GM judgement. If you don't lie then you can evade having to make a Bluff roll. I think Call of Cthulu handles it far better with a broad 'Fast Talk' skill.
The difference, I think, is that there is a chance they figure it out because they then get to roll. But maybe that's not a big difference.What's this difference between this and just limiting when a player can learn something with a passive check. For example, unless they have a reason to suspect an NPC is lying, passive Insight doesn't apply. It's not just that your passive perception/insight picks up everything ambient in the environment, rather it draws focus to things you're paying attention to.
Why I like rolling Insight, Bluff and stuff is because it is more fair. Social interaction is more or less common on adventures and if the players at the table knowing the GM better or having an awesome perception for such things always have the advantage of determining whether the NPC tells the truth or not, this shifts the balance.
[. A common trouble with puzzles in D&D is there's little inventive for the PCs to actually engage with the puzzle's headspace; instead the payoff is usually in figuring out a way to avoid it altogether and still get where you want to be.
Same as in combat, if a player knows the combat rules, knows how to min-max, knows how the DM uses monsters, knows to use good tactics, etc. Player skill is involved in winning combats, why not in social interaction?
It is involved. When to request an insight check? How to min-max your social skills? How to play out social interaction, because a good one usually gives a bonus (at least it should)?
Unless you have a pixelbitcher DM who shuts down every option other than solving the puzzle, *sigh*. I got really frustrated playing an INT 8 Dwarf barbarian recently, we were trapped in a room with a complex solve-or-die puzzle. The DM made everything in the room immune to my maul - and I was easily doing 20 damage/strike - including the doors - and all the furnishings - to ensure there was no way out other than by solving the puzzle. It felt like I was trapped in a CRPG.