I'm going to ramble a bit here - sorry if it isn't fully developed, or coherent.......
I suppose it depends on what you're looking at - almost all of the fakes are copies of a handful of newer model Rolexes. I guess there's a more recent trend now where lesser Rolexes are tarted up to resemble the really rare and valuable stuff, but an "ordinary" vintage piece is far less likely to be faked. I find it interesting that the majority of interest with this brand seems to be focussed on the same watches - Submariners, GMTs, Daytonas, Datejusts and Presidentials (which I find kinda boring, but that's just my opinion, and it probably has to do with the fact that I don't really want something that everyone else wants/has...and can't afford one....). Which are exactly the models that the counterfeiters churn out. It's to the point where when one sees one of those models, you assume that it's fake, with a very slight chance that it might be real.
Happily, that's not the case with the majority of watches that Rolex has made. The vast majority of vintage Rolexes are authentic, and it isn't too difficult to tell when you look at one carefully. I knew when I saw my Everest that it wasn't a fake, same thing with my Lipton - they simply aren't watches that anyone fakes (yet, and hopefully probably never will). Part of it has to do with why people buy Rolexes (the "look at me" factor, the bling-bling factor, etc.) and what these watches represent for and to many people (success, luxury). The vintage watches aren't really very "Rolexy" - they often aren't immediately recognizable, have next to zero "bling-bling" impact, and are impressive only to those that know their watches, and appreciate them for what they are, not who they impress. No one at the office comments on my Lipton, and women at the club don't fall all over themselves to get down and dirty with my Everest. Just doesn't happen. And I don't wear my watches for those reasons - so it's all good.
Rolex has done a tremendous job of marketing it's name, globally. It is by far the most recognized "quality/luxury" brand - which is a double edged sword. It keeps prices high (good resale value, solid investment, exclusivity). It's a cultural icon. But it also sets the brand up for reverse-snobbery - WIS's resent the brand because it is successful, and everywhere, and because everyone knows Rolex. Also because most WIS's know that Rolex really is a mid-range watch priced high because of savvy marketing - but to the lay public, Rolex is the best (and they're willing to pay the high prices for a watch that probably shouldn't cost that much). And despite the fact that a Brand X watch might be equal to or superior to Rolex in quality, design, cost, exclusivity, etc., the myth overtakes truth, and the Rolex holds its value (or even appreciates), has the "ooh-ahh" factor, while Brand X is left in the dust. Which pisses off people that know their watches, and hate the fact that no one knows what their Grand Complication, Tourbillon, etc. is, or gives it any attention, but the guy with the fake $200 Submariner gets noticed by the bling-bling wienies. They have no idea of what the real horological masterpieces are (probably have no idea of what "horology" is either......the study of ladies of the night?). It has led to an explosion in counterfeiting. They're exclusive, but they're not.
Anyways, these are just thoughts - i certainly wouldn't stay away from Rolex - just do your homework, and check carefully before you purchase.......