In this episode O'Brien, Data and Troi are under the influence of energy-spirits of prisoners trying to escape, and they take the people in Ten Forward as hostages.

At times (when Troi talks with Picard) it seems that Troi senses Picard's feelings ("I know you don't believe me") but in that case wouldn't she have sensed the deception when Picard was saying he'll cooperate ( when he wasn't intending to). Wasn't his reason for being there to buy time or figure something else out? (At least that's what he told Riker).

I don't remember the episode exactly, so there may be mistakes in this question, feel free to point them out. :)

Theoretically, Troi should be able to sense deception, but either the writers chose not to care about it for the benefit of the story, or they forgot. Perhaps with the "spirit" in her, the empathic senses were dulled, and Picard may have been able to block out some of her probing.

i would have thought she should be able to as if your being deceptive it envokes emtion. she can tell when someone is lying so why not decptive?

I would chalk it up to the new entity either not knowing how or not realizing Troi had those capeabilities. I assume as spirits theyd have telepathy also, but It may be very different.