Although I disagree completely with "avoid Mexico at all costs", kidnapping is a real threat. They won't kill you but it's a pretty unpleasant experience, and avoiding cocaine won't protect you.
Which states are you seeing foreigners kidnapped regularly?
This is anecdotal, I have family in Mexico City and many of their friends have been kidnapped. I'm not sure about foreigners specifically.
Anecdotal - I lived in Mexico City for 2 years running around doing very stupid things. Only kidnapped once, by the police, for less than a few hours, because I was doing illegal things in public.