It just makes sense that you should always be suspicious of traps. After all, a trap is designed to capture or hurt you. Of course you shouldn't trust one.

Given that, and the fact that traps are often concealed or not obviously traps, it makes sense to always be suspicious of anything that might be a trap, or that looks like it might be a trap.

And given that traps can be concealed anywhere, it follows logically that you should always be suspicious that everything is a trap.

Roleplayer logic at its finest.

Transcript

GM: You come across a dead animal spiked on a tree.
Luke: Some sort of trap, I reckon.
C-3PO: Oh dear. How crude.
Chewbacca: We walk around it.
Han: Unless... that's what they want us to do.
Luke: Huh?
Han: It could be a diversion, to take attention away from the pit trap in the obvious path around it.
R2-D2: I think I've seen this in a dungeon module. I check for traps.
GM: <roll> You don't find any. Other than the meat on the tree.
Chewbacca: We ignore it and follow the tracks.
R2-D2: Hmm. Could have been a low skill roll. Luke, use your Survival: Forest skill.
Luke: To do what?
GM: Your extensive forest knowledge tells you that forest dwellers often set animal traps to capture food. And that therefore there may be some forest dwellers in the vicinity.
Han: Well I don't want to be forest dweller food. There's no way I'm walking around this "trap" now.