PV is my favorite of those ports too. Shame.
I know that one murder in Mazatlan happened directly in front of the cruise terminal. Near the gate that everyone uses to go over to the Walmart. You can't get any closer than that without being inside the port security fence itself. I think that one was the final straw that caused Carnival to leave.
AcaKev-I don't think the lack of acknowledgement of the crime there by the posters here are because they are promoting tourism, they are just travelers/cruisers who honestly believe that it is not as bad as you are saying. It's an easy problem to ignore, no one wants their cruise vacation spoiled with facts.
Comparing crime in the U.S. to Mexico is moot. When a crime occurs here in the US there is a very good chance that it will be investigated and solved. That is not so true in Mexico, thus it goes on and on.... Plus the rates can be higher here because crimes are reported here...many many crimes are NOT reported in Mexico. The TRUE crime rate would shock people.
Now, will this information keep me off a Mexican cruise? NO probably not, but I want to be as informed as possible.