Don't know how to flag spoilers, but there is a minor spoiler about a Kings quest
I had a character with a high barter and i was doing a kings quest. There was a (violent) dispute going on between NCR and the kings in Freeside. I went to the NCR and found out what happend.
As i entered the kings building to go and report about the situation to the King, a King-member approached me, the conversation went something like this(K=King gang member / M=Me):
K: Hey, you might want to keep your mouth shut about what happened.
M: What's it worth to you?
K: You're just like everyone else around here, but thsi way i know you'll keep your mouth shut; heres a 150 caps.
M: [BARTER] How about you double that amount.
He gave the extra caps and i was like "damn, what a svcker

"...first thing i did was tell the King all about what happened.