I returned last week from a six day fishing trip to the SE corner of Mexico. Flew direct from DFW to Tulum, which turned out to be a great airport, newer and without the nonsense of Cancun.
We drove to Mahahaul about 2.5 hours south on 4 and 2 lane highways, then another 1.5 hours on gradually deteriorating roads ranging from broken asphalt to eventually a dirt two track. Spent six days chasing bonefish, tarpon, permit and snook. Outstanding fishing!
A couple of observations, I deployed multiple times to Central and South America in the late 80's and early 90's working counter drug missions for Uncle Sam. I also spent a number of years working drug trafficking along the Texas-Mexico border, including temporary deployments into Mexico. I mention this only to reference my background in evaluating third world threat conditions. That and a couple of $$ buys a 7-11 coffee, nothing more.
Currently, I would not go to any western state in Mexico or any Mexican border state. Cabo and the eastern Baja shore maybe an outlier. Loreto is a great place to fish, and Magdalena Bay looks very promising. I would avoid larger resorts in the tourist areas and I would definitely not venture outside the resort to see the "local" sights. The place I stayed has a capacity of 10 anglers and is located in a village of approximately 30 souls. Do the owners probably pay a cartel tax, sure. Is it an area where rival cartels may clash, probably not. However, anything can happen.
Merida was on my list for tarpon fishing in the fall, but the impact of a recent oil spill doesn't look promising.