I guess in Mexico you have to use your common sense when the sun goes down.
When we were in Puerto Morelos I was feeling safe like in my own home. There were no police present on the street however the Police office was adjacent to the main square and that is where everybody spends the late hours....and I mean everybody...from little children to older folks, Mexicans and tourists. I would feel comfortable there even if I was by myself. Puerto Morelos is as happy place as happy it can be and during our week long stay it never crossed my mind that I should watch over my shoulder.
On the other hand in Valladolid you see lots of police present not only on the main square but they are visible every two streets. You could probably scream "Police" and they would say "Yes, can I help you" hehehe. Just by looking at the Police force in Valladolid you can see that they operate professionally and it is a daily routine. Valladolid is also a busy town, there is plenty of Mexicans in all ages present on the street and most of them does not look as "well off" as Mexican residents of Puerto Morelos. I don't know what is the issue with Valladolid. I assume that there is some crime since you can see uniformed men and women present on every second corner (even the non-busy streets). I also was looking over my shoulder when we started wondering away from the main square as it was quite empty and the sun began to set. I can't tell you why I was looking over my shoulder...was it a common sense or was it something else....after all we are fed stereotypes aren't we?
One night we went also to the Mall (yes Mall) in Playa del Carmen....to see how is the Mexican mall...is it Mexican or American....well it was pretty much American and empty. We did felt comfortable as for our safety, and we did felt disappointed ....as for how Mayan people are chugging down Coca-cola and all other produce stuffed with high fructose corn syrup.
As for driving at night I did not see any reason why shouldn't we do so. Yes you have to be aware of the speed bumps that are invisible at night and you have to watch out for local people biking home after too much tequila. There was also some road kill here and there....but isn't it the same back home...wherever your home might be?
SO, USE YOUR COMMON SENSE AT NIGHT AND FEEL FREE TO APPLY ALL THE STEREOTYPES, after all you are on vacation and you supposed to come back relaxed and rested....you did not go to Mexico to "prove something".
Dress code? it is not a code but friendly advice.
At least in December (don't know about any other time) I would wear long summer pants (light fabric) and long sleeve shirt.
It is not only chilly at night in Mexico, but there is also plenty of mosquitos waiting for your sweet blood, and believe me they love DEET too. I had really strong mosquito repellant on me and got about 50 bits in my legs one night.








