Sometimes what you think is conventional wisdom is just a plain misconception. Here are some of the biggest myths about getting cheap airfares:

There's a "magic" hour (like 3 a.m. on a Tuesday) to find the best prices: This is the biggest misconception of all. Airfares can change minute-by-minute and day-by-day, as can seat inventory at the lowest fares. This is especially true now that consumers can put non-refundable fares on hold for 24 hours with no-penalty cancelation. If someone buys the cheapest seat on the plane at 11 a.m. on a Thursday and cancels at 10 a.m. on Friday, that seat might go back into inventory and can be yours if you happen to be searching at 10:10 a.m. The trick to finding low airfares is to sign up for free airfare alerts and to search several times a day.

Fares are lowest on Tuesday and Wednesday: While it's true that if you fly on a Tuesday or Wednesday you'll get the lowest fares, it's false that you can only buy on those days to get the best deals. True, many airlines launch advertised sales on Tuesday but the unadvertised sales are much better and they can pop up route-by-route at any moment.

Last minute fares are always more expensive: That's usually true, but not always. Especially for travel to foreign destinations, you can sometimes nab huge fare reductions at the very last minute. A great place to track these deals is on Google.com/flights/explore.

All airlines match each other's sale fares: Simply not true. Often, one airline will have a fare on a given route for hundreds less than all the rest.

Airline mergers mean there are no fare wars anymore: Although fares have gone up somewhat with airline consolidation, there are still fare wars. United will lower fares to Hawaii, for example, from American's hub airports such as Dallas and Miami, and then American will return the favor from United's hubs.

Travel agents are useless for finding low fares: Travel agents have tricks up their sleeves that automated websites have never heard of. For example, if New York to St. Barts fares are $800 round-trip, a good agent will sell you a $250 fare to St. Martin and then a cheap high-speed ferry to St. Barts, or a separate airfare from St. Martin to St. Barts at big savings.

Non-refundable airfares are always non-refundable: In addition to being refundable without penalty within 24 hours of booking, non-refundable fares are fully refundable if the flight is canceled or if it's significantly delayed, or if the airline makes a significant schedule change before you depart.

You have to buy a round-trip fare or stay over a Saturday night to get the best deals: That used to be true, but no longer. Many airlines now sell one-way fares for exactly half of the lowest round-trip fare.

Clearing your browser's cookies results in lower fares: I've never seen any solid evidence of this.

There are still bereavement fares and senior and child discounts: Most airlines have gotten rid of these, and where they still exist the discounts are so paltry that they're a joke.