Mercenaries should of course be... mercenary. Any opportunity to turn someone else's misfortune into a quick buck should be grabbed and made the most of. There's no need to be impolite about it though. That's the one mistake PCs often make. Why raid a cave system full of goblins, slaughtering all before you at considerable risk to life and limb, when you can simply rock up to the front door, make pleasant conversation about how nice a cave system it is, and how it'd be a right shame if anything were to happen to it, while meaningfully picking your teeth with a two-handed sword?

Transcript

Chewbacca: What my good captain means is: When you are ready to move on, we shall take you to a nearby system of your choice.
Chewbacca: For only a small additional fee.
C-3PO: What terrible seismic event could have done this?
Han: Well... it could—
Obi-Wan: This was no geological accident. This is an act of war. Something blew up Naboo.
Chewbacca: I hate to interrupt, but we have an incoming blip on the radar. It looks rather like a short range fighter.
Han: Mass murderer! I shoot him down!
Chewbacca: It's out of range.
Luke: Look at him. He's headed for that big space station.
Obi-Wan: That's no space station. It's... the Peace Moon!
Han: After him, Chewie!
Luke: Are you insane?!
{insane look from Han}