Well, you can't really dictate PC's actions based on an Intimidate (or Bluff, or Diplomacy) check, like you can an NPC's. I've seen two good strategies for dealing with these situations. (They work best in tandem.)
1) Represent the NPC's actions in ways that are reflective of their check result. Someone with a good Intimidate roll is portrayed as dangerous, a good Diplomacy roll indicates they seem friendly and helpful, a good Bluff check means they seem honest. Without information to the contrary, PC's will be wary of an NPC who is described clearly as a bad-ass m-f-. Which is what you want. This works better if most of the NPC's portrayed this way really are dangerous ...
2) Doubtful PC's get to make a Sense Motive check. Rolled secretly by the DM, of course. A successful check gets the PC the useful information that the NPC is inflating his power/trying to influence them/lying through his rotten teeth. More often, the check will be unsuccessful (how many PC's put ranks into Sense Motive?), and they'll get no information; or they'll miss by x (5, 10, whatever) and get false information. ('Oh, yeah, he's at least as dangerous as he seems!')