What about highly-perceptive-but-still-normal characters? Often people who can see the truth in everyone around them have very little patience for pretense. Examples:
-In Buffy the Vampire Slayer, Spike can always see what people are really feeling (though he doesn't usually care). He calls Buffy and Angel out on their just-friends act with an epic speech: "You're not friends. You'll never be friends. You'll be in love till it kills you both. You'll fight, and you'll shag, and you'll hate each other till it makes you quiver, but you'll never be friends. I may be Love's bitch, but at least I'm man enough to admit it."
-The Mentalist - Jane is constantly calling Grace and Riggs out on their obvious attraction to each other, despite the discomfort it causes.
Edited by Laecy
What about for when someone's "sensors" indicate that you have tapped that? (e.g. Reynardine and Coyote of Gunnerkrigg Court smelling Parley and Smit's scents on each other.)