everyone has an opinion but I have never seen any evidence to support any of the theories. Other than 9/11 I would not look with any preconceived notions. I just take my time and look every day once I decide when I am going. You need to do the leg work unfortunately and its a pain but lots of looking has always rewarded me with a good price. Flying into POP is more expensive than SDQ but if you factor in the dangers, time and costs of getting out of the SDQ airport to POP it works out to be the same. POP is a much safer airport than SDQ.
I am retired and can easily organise to travel at any time of the year. All the booking agents who advertise special deals to where ever never tell you when. Anybody know of any company who will tell me WHEN it's the cheapest to fly?