Karl sent you a pm did you get it?
They are usually watching to get an idea of the selling price, either to sell their own or to buy one at a future date.
Sell on eBay, buy on Autotrader. At least that's what I do and always have a lot of watched similar cars I intend to sell.
What I have found out is that bidding lists are more watched and viewed compared to fixed price or classified ads.
I had a car for sale on pistonheads for one month and not even 1 call was received, popped it on eBay and no joke it sold within 10 minutes and the guy picked it up the next day. Crazy!!
My 2.3-16 had 112 watchers when it was last up for sale so not uncommon to get that although I think poormansporsche has the world record!