Not only that, but what do you suppose they could do to the candy undetected to taint it? I suppose they might try using hypodermics to inject poison/anthrax/smallpox into the candy, but they'd have to be very careful not to leave an obvious hole.
Oh boy. Let's hope this is just a coincidence. Maybe the men were just trying to restock their convenience store in a hurry, and didn't have time for the niceties of a valid card? Not that we shouldn't try to track these guys down, but perhaps the simpler explanation in this case is the correct one.
Convenience store owners, or their employees, either have accounts with places like Costco and Sams, or pay by check, not in cash.
The same way they distribute anthrax now: send out a lot of "packages", but only load up a small percentage with the real thing. In this thread, there's a report of an arab buying a large quantity of candy, then returning it. The police "checked" it, and then it was put back on the shelf. Does anyone believe that every piece of candy in that lot was tested for every possible contaminant?
I am advising everyone I know to not by any halloween candy, and to not allow their children to accept any -- even "from people we know", since it can be tainted at the retail level.
I had to get a shot a few days ago - the first time in years - and I hardly felt the needle its was so thin. I suspect it wouldn't be too hard to do it and still have it go undetected. When I was a kid we just looked for opened wrappers. Anything that appeared sealed (like those bite sized Snickers bars) I wouldn't look twice at.
Of course, another thing to note is that they wouldn't have to do anything to the candy to make everyone paranoid. Just the fact that some suspicious people have bought large amounts of candy is in and of itself sufficient to cause widespread fear.
All we can do is pray.