How would one distinguish the ordinary mask-wearers from the bandits?

Dear Editor,
The Swine Flu epidemic which is affecting Mexico has triggered some advisory health warnings globally and locally, but I am concerned if we have to press the red button to wear face masks.

How would we differentiate the bandit from the genuine mask wearer? A contingency plan should be put in place not only locally, but regionally, where crime is higher than in some parts of the world. I trust that it never happens, but the current precaution is in order since we commute to many of these countries very often.
Yours faithfully,
(Name and address provided)