Not necessarily a person who knows a lot about watches, it more like the type of a person like the list below.
WIS = Watch Idiot Savant.
1.A person self trained to sleep in 5 positions while wearing his/her COSC certified chronometer in bed.
2.A person who opens the back of a new Patek on the first day of acquisition and hand winds the rotor to tighten up the main spring to save wear on using the winding crown.
3. A person who takes his 2000 meter water proof Rolex SD off from the wrist. And puts it into the deepest pocket, and nine plastic bags before walking into a rain storm without any rain gear on.
4.A person who waits every 5 minute in front of his radio controlled clock in order to adjust all his/her 14 mechanical watches to the accuracy within -2/+2 seconds per 24 hours.
5. A person who can memorises all serial numbers of the Rolex watches made in the past 60 years but keeps forgetting the wife's wedding anniversary.
6. A person who washes his/her watch in luxury shampoo,polishes with specially bought cloth,then rests it on another specially bought cloth just encase they scratch the stainless steel.
7. A person who buys loupes and microscopes to look for the miniscule differences on dials, and look for cats whisker size so called alignment point differences.