Perspicacious

Etymology

From Latin perspicax, "sharp-sighted," from perspicere, "to see through" (per, "through," + specere, "to look"). The literal act of seeing through something became the metaphor for penetrating insight.

adjective · /pur-spih-KAY-shus/
Perceptive; quick to notice and understand what’s really going on.
What it names
The person who sees the subtext everyone else misses — sharp-eyed about people and situations.
Example
One perspicacious question from the back of the room unravelled the whole pitch.
Related idea
Don’t confuse it with perspicuous, which means clearly expressed, not clear-sighted.