Rolex Deep Sea Special watch - GIF

[Toolmaker51]

Probably because it was strapped to her arm

People notice details, often those who's livelihood relies on appraisals. Might be a lathe, house, oil rig, even a rusty anvil.
When it comes to Rolex, aside from trademark, some features too. One is distinct from common quartz watches, the second hand appears to sweep the dial; but actually tiny split second movements, like a analog chronograph, or most electric clocks.
Bulk of normal wristwatches and battery clocks move second by second.
Listening to one held to your ear a real giveaway, not ticking but kind of a humming tone.

In the world of counterfeits, a lot of effort goes into duplication. Dealers and pawn shops pick out fakes that look very real; but not the movement.