This whole problem seems to me to be worthy of pretty serious consideration -- perhaps in S&T.
This is not random street crime, or even home-invasion type stuff -- which is bad in itself.
However, the folks whom you might meet in a pot field or meth lab are a kind of threat that takes things up a level. For one, they're likely to be heavily armed. At least, logic would lead me to believe so. Anytime you have a product with a street value estimated in the many tens of millions, serious weaponry becomes quite affordable, and the value of that product is worth defending to the death.
Second, it seems unlikely that there will be only one assailant. You might encounter only one, at first, but there are likely to be at least a couple more, and perhaps quite a few. And they will have some means of communication with which to warn the others -- even if the shots you may exchange wouldn't bring the rest anyway.
Third, unlike street crime or home invasions, these guys can't flee the area in the hopes that they can't be identified. They have an investment that is routed (ha ha) to the spot. If they see you and you leave, they'll lose that multi-million dollar profit. If you vanish, they may lose it anyway if there's a detailed search of the area, but a lot of hikers don't leave good info about where they're going and it's more than possible that the searchers would never approach the right area. In any event, if you don't leave the hillside, they've got several days to a week, maybe, to salvage as much as possible of their crop and split.
All that to say, these guys will be armed, numerous, at least somewhat coordinated, and HIGHLY motivated to kill whomever enters their area.
This is pretty frighting and seems to me to go a bit beyond the average S&T discussion.
It also seems to me to be very distressingly LIKELY to actually happen to some of us.
I'm going to start an S&T discussion on this. HERE:
http://www.thehighroad.org/showthread.php?t=471761
-Sam