Just to venture slightly back on-topic and away from the compelling world of wife beaters, I don't think how you dress is really a reliable indication of whether your watch is real or fake. Now, that being said, I think if you're dressed in a brand new Brioni suit, you're much more likely to have people assume that your Rolex is real. But the converse isn't necessarily true. To use my favorite icon, look at Bond in Casino Royale. When Bond was running around chasing acrobat-criminal-guy, he was wearing fatigue pants, a truly awful Hawaiian shirt, and an Omeeega. Just because he's dressed crappy doesn't mean that he's wearing a fake Omeeega.
To go back to the OP's point-- I believe Occam's Razor applies here. That is, the simplest explanation is usually correct. Here, you've got a professional jeweler (and, not incidentally, a professional douche). He sees something on Maxse's Breitling that tips him off that it's fake. He can't quite put his finger on it. He confirms this by handling the watch, but again, can't articulate exactly why he thinks it's fake, so he makes something up. Alternatively, he's just a moron who made a lucky guess. Either way, he spotted a rep for being a rep.