Well yeah, it's generally obvious when you fail a Deception check due to the reaction of the NPC (and when it's not, that's what Insight is for).
Han: Uh, everything's under control. Situation normal.
Voice: What happened?
Han: Uh, we had a slight weapons malfunction, but uh... everything's perfectly all right now. We're fine. We're all fine here now, thank you. How are you?
Voice: We're sending a squad up.
Han: Uh, uh... negative, negative. We had a reactor leak here now. Give us a few minutes to lock it down. Large leak, very dangerous.
Voice: Who is this? What's your operating number?
Han: Uh...
[Han shoots the intercom]
Han: Boring conversation anyway. LUKE, WE'RE GONNA HAVE COMPANY!
Han knew he failed his Deception check. For all it mattered. He aint getting a re-roll.