How to recognize a fake sub?

I am just wondering what is the best way to go when doing a private deal with a submariner, and you have the advance of having the watch in your hands. What would you look for as signs that the watch might be a fake.

I know that the best way to check is also opening the case and looking at the movement, but the tips I want to get from you guys is assuming that the watch can not be opened.

From what I have read before:

1) Check the threading and rubber seal on the crown that it has to be sharp and defined.
2) Check crystal for visible scratches (should not have in the sapphire models)
3) Check serial and model between the lugs and contrast it with paperwork if possible
4) Check clasp for visible error where the flip lock closes and the clasp (it must be round and soft)
5) Check for clasp code that should make some sense according to the model year and serial of the watch
6) Check the Rolex symbol laser etching in the crystal (if possible depending on the year) + check for S letter in the etching if the crystal was replaced.
7) Check for the crown the threading (where you grab it to turn it) should be sharp and well defined.
8) If you turn the crown clock wise, the hands advance forward (??? I believe is for newer models this way)
9) Check for quick date jump by changing hour manually
10) Any tips on lettering on the dial like 300m (the m) should be right over the m in Chronometer.
11) Check the almost inaudible ticking of the movement against you ear
12) Make sure the seconds hand is not jumping in 60 times per minute
13) Check the 120 clicks of the bezel
14) Check bezel is unidirectional (anti clock wise) movement
15) Movement of the minutes hand should be smooth not jumpy when setting the hour
16) Sharp corners on the bezel markers
17) Smooth curve in the extension link lock
18) Check correct magnification 2.5x of the date under the cyclops (date should almost fill the cyclops window)
19) Printing of the date font should be sharp well printed
20) Check for weight of the watch (should not be super light)

I am sure the experts here have more tips to share that would be very useful (at least to me) when doing a hand to hand deal.