OMG you walked to Americas Mall in that heat??? Even if it wasn't that hot I think that walk would kill me lol.
Never felt threatened in Cancun or Playacar !!! We hear the exact same things from MOST of our friends and Coworkers!!! "YOU ARE GOING TO MEXICO, My first cousins friend just got back from there and they barely escaped with their lives" !!!!! 99% of the people that complain about Cancun have never been to Cancun. I love to them them "Worst things that might happen are : Getting sunburned , Getting too Drunk, Getting hugged by a topless gal".
Been to Cancun and Playa Del Carmen 8 times over the last 15 Years (was even married there) not once have we ever felt threatened during our time there.
I feel safer in Cancun than I do my own home town! But usually people who have never been are always the first to "warn" us about Mexico. As with the rest of the world, there are places you should and should NOT go.... I tell everyone not to worry, we are smart and haven't had an issue in the 10+ times we have visited!