It just so happens that in this case the particular vehicle for obtaining gain through false pretenses is an MB watch, but like all internet/e-mail scams, it's nothing to do with watches, but all about relying on people's greed. The rules are simple;
1. If it seems to good to be true, it is.
2. If a stranger contacts you, it's a scam.
3. If they are offering easy money or gain, it's a scam.
4. If any angle relies on your greed, it's a scam.
5. Rule 1 always applies.
You all almost certainly know this, but it never helps to remind people.