If you want to be a bit more careful, look a bit deeper into the feedback to see what recent seller transactions look like. I think I can remember some watches which looked too good to be true where the guy has some positive feedback (say 30-40) but only been on ebay few months and all the entries are where the guy buys a pencil for 25c or batteries for $1 or something trivial like that.
But I would echo the guys, I've had some disappointments but no cases of outright not receiving the watch (so far). And many of the disappointments come from "irrational exuberance" in my bidding and expectations.
Oh yes, and if you are collecting Heuers, 30 mins of researching OtD a week is a decent vacination against fakes & frankens.