Might have wanted to read whatever backstory the DM stuck on this guy.

Could have been really helpful here.

Or...
He's going to make up the backstory on the spot >.>

Yeah, you have a NPC, yout hink he is lying, but you rolled crap in your sense-motive so you can't verify it for sure...And you spend your time being suspicious about the guy 'til one of you is dead.
At least here he know for that the guy is lying. though, he don't have a in-character way to know it, so that's a good thing Tashigi's with him.

Story time! Tell a story of someone’s use of the Appraise skill.

Haha, I needed something falsely appraised, so I went to a reputable merchant down at (roll...Jocund's Oddities) - not to ask if something was worth a fortune, but to get the guy to put in writing that the item was indeed a sword. Because someone can't tell the difference.

And the DM was happy to get the guy to smugly sign it.
DM: "YES. This is OBVIOUSLY a sword. Signed. MAXWELL. SUUUUUPER GENIUS."
Me: "I thought the sign said Jocund's Oddities."

*scribble, rewrite*

One forgery later, I had verification that I was carrying the lost sword of the king.