Party paranoia wise, this works best when you have a listing of all the skill ratings of important 'behind the screen' rolls you'll have to make and just roll without telling them what skill check you're using.
Or ask "Hey what's your perception rating?" and then roll, even though you don't have anything you're really needing it for. So even if they freak out at 'take 10' you can still go, "Nothing of note" cause there wasn't anything in the first place.
For sense motive and lying, I tried to remember that just because someone doesn't want to talk to you, doesn't mean they have to lie to you. "I don't want to tell you, go fark yourself" can be a legitimate response.
Or people lying without knowing they're lying.
Or omitting things.