I'm not sure anyone here actually knows what your point is.
I am fairly new to this hobby so I'm pretty sure that a great rep could probably fool me if I wasn't given anything to compare it with.
But, and this is a big BUT, you have to realize that some of the members here are incredibly knowledgeable about certain models (more so than some ADs, that's for sure)
I think it's definitely easier to spot tells on a movement rather than a dial. Movement have always been harder to rep than dials. imho
You have to concede that there are people out there that could very easily spot a rep at a glance. Not every model of every manufacturer of course, that is an unreal expectation. But for many people, watches are their passion and they are obsessed about a certain brand or model and know virtually everything about it. Is that so hard for you to comprehend?
Back to your "point", if you don't think that it's possible to spot a rep in under a second, why not give your U-Boat to Italo Fontana and see what happens?