In most places where we have had a deceitful NPC, it has generally been the onus of the GM to present them as honest and reliable to "fool" the players into believing that their intentions are good. There is generally no roll for this, as it would give away the dishonesty. The only cases where we might do a roll is if the intentions of the NPC are visibly dishonest and they are using magic (or even social "magic" ala a cult leader) that is pulling the PCs under their sway. This would be known to all, and is generally short-term.