I feel that we're more likely to be able to spot flaws, but many people that I know are very, VERY aware that 99% of the Rolexes on the market are fake. Regardless, most people I know who own gens (including myself) wouldn't "call" someone out on having a replica watch simply based on common courtesy. If you can make someone's day with a compliment, who cares whether or not the watch is a replica?
...Now, when someone decides to try and tell me that my gens are "fake" WHILE wearing a rep and having a holier than thou attitude, I'll go right for the throat