If there's anything that can get players more paranoid than a GM making secret notes and cryptic comments to himself, it hasn't been invented yet. If you're a GM, try it. If you're a player...

Run away!

Transcript

GM: The advanced battle droids fire!
Qui-Gon: I deflect it with my laser sword.
Obi-Wan: Me too.
GM: The blasts bounce off their shields.
Qui-Gon: I attack back.
GM: Your swords bounce off their shields.
Obi-Wan: The sword can cut through a blast door but not the shield?
GM: It's a cutting-edge war machine and you expect it to have no defences against a laser sword you bought in a bar? Of course it's not going to work. Otherwise there's no sense to this campaign.
GM: They fire again.
Qui-Gon: We can't hurt them, and they can't hurt us. Might as well go back to opening the blast door.
GM: Sure. By the way, these droids have rapid-fire weapons. What did you roll for your parry?
Obi-Wan: 14.
GM: <scribble scribble> Interesting.
{beat}
Both: Run away!!!