They don't take anything I say in character as the GM at face value.
Example 1:
They unknowingly stole the ship of a Black Sun Vigo (someone else told them it was his ship and they could have it). The Black Sun Vigo confronts them, pulls them aside with a large entourage of heavily armed men, and interrogates them. He understands the misunderstanding, but asks for 25k credits as a down payment on the ship, and requires work from them going forward.
My group has about 30k credits between them. They lie and say they only have at most, 2500 credits on them. Realistically, I couldn't think of any way the Vigo could have known they were lying outright, so I let the player roll deception. Can you believe the stats in the back of the book for Vigos have no ranks in discipline? Anyway, I add 2-3 setback dice for the situation, remembered Nobody's Fool, and the player still succeeds.
I put this encounter in there to get credits away from them as I made the mistake of giving too much to start. I put them in a room with a powerful crime lord, one of his top lieutenants, and 4 heavy blaster rifles pointed at their heads. They lie their way out of it. I think I'll have to damage their ship. Repairs are costly and don't have a lot of negotiating room.
Example 2:
They were tasked with capturing a pirate. I basically did Trouble Brewing from the back of the Core Book, except their employer wanted him dead and offered more money than the Imperials, but only if he was alive. Well they killed the guy, but got the 2k reward from the Rodian for the droid which made up most of the difference between their employer's lower price and the Imperials (they didn't realize the Imperials wouldn't pay up) and took the body to their employer.
Their employer made a simple comment lamenting that he wished he could have questioned the guy before he died, but would still pay out the lower rate. The player took this and ran with it. What did you want to know? I might know what he knew, how much would you pay me? Etc.
I stopped him before he could get all those questions out, because I knew it wasn't something that their employer would accept, but I felt like if I played it out as the employer, the player would have kept pushing, and searching for some way to get more money out of the guy without realizing the guy wasn't interested. I hate saying things like, "As the GM, no that won't get you anywhere."
Example 3:
Their ship is approaching the space station they are headed to and the docking bay hails them and reminds them of the 200 credit docking fee. The party has around 10k credits per person. The Wookiee performer immediately jumps on the comms and tries flirting with the guy to waive the fee. And he doesn't stop when the guy on the other end says that's the fee.
Everything has an angle, a sidestep, or a way for them to profit and it gets rather frustrating as the GM. I feel like I have to keep breaking character and telling them GM to player it won't work. Then the one player says when I do that he shuts down and gets less interested in doing anything, and then the group misses things they are SUPPOSED to chase after.
I'm friends with these guys, so I am comfortable talking to them, I just don't know how to get my point across without sounding like they suck at playing and need to play my way.