You can tell inexperienced roleplayers from experienced ones quite easily. Put them in a room that might contain traps or lurking monsters.

The inexperienced players will check behind the furniture, under the rugs, around the walls, etc, etc. The experienced players will check the ceiling. All the worst things are concealed on the ceiling. Really experienced players will have a 10-foot pole handy, specifically to poke and prod the ceiling, just to make sure it doesn't have any lurking monsters, collapsing sections, more lurking monsters, cunningly concealed deathtraps, even more lurking monsters, rusty spikes that might drop on you if you so much as breathe, and, of course, yet more lurking monsters.

And you can tell veteran adventurers in most fantasy worlds by the way they keep glancing up every few seconds.

Transcript

Qui-Gon: I look around carefully to make sure we're not being followed.
GM: There are townspeople wandering around the market, but no one is paying any attention to you.
Qui-Gon: I look everywhere.
GM: You don't see anything suspicious.
Qui-Gon: Including the ceiling.
GM: You're outdoors. There's no ceiling.
Qui-Gon: Anything in the sky?
GM: No.
Qui-Gon: Do I hear anything behind me?
[SFX]: wmm-wmm-wmm...
GM: You faintly hear the sound of a droid some distance aw—
[SFX]: wmm-wmm-wmm...
Qui-Gon: ATTACK!
[SFX]: Whooom!!
[SFX]: 16!
[SFX]: Krzzshh!!
Anakin: What was that?!
Qui-Gon: Is it dead?!
GM: <sigh> A black spherical droid lies neatly bisected on the ground.
Qui-Gon: I poke it.
Qui-Gon: Is it moving?
GM: A small spark erupts from its smoking innards.
[SFX]: fzzzt...
{Qui-Gon loks around silently in paranoia}
Qui-Gon: We run.