This really depends on many factors, kind of a cascading case here:

Do you know why the PCs are looking for you?
YES > Respond appropriately

NO > Do you have some false idea about why they're here?
YES > Respond appropriately to what that idea is (ie: if they're here to kill you, get out of dodge)

NO > What's the reputation of the adventuring party? Have you heard of them? Are they the type that would kill your type (whatever that is) or what?

YOU KNOW OF THE PCS > Respond appropriately

YOU'VE NEVER HEARD OF THESE GUYS > What's the impression you get from the PCs? Are they a mix of trusted races? Are they all donned in scary spiked armor and dark clouds? Are they threatening the locals or are they benevolent?

Respond appropriately.


This doesn't take into account what type of personality you (the NPC) have as well. Are you paranoid? Brave? Confrontational? Scheming?