One passenger told us, "They always mark it up, or there's always some taxes involved."
Another said, "It's never a straight-up deal."
And a third explained, "Usually the deals I get are not where I want to go at the time I want to go."
When you try to snag a great airfare online, sometimes it can vanish into thin air.
That's what Consumer Reports' Tod Marks found when he investigated how to cut the cost of flying.
Tod says, "You see a lot of airfare deals out there that sound great. But hidden fees, fine print, and blackout dates can make locking in a great deal as tricky as a soft landing in turbulence."
Take this Travelocity "deal" on a round-trip flight from Philadelphia to London for $277 dollars. Once you book, it actually costs almost $666!
Tod explains, "Spirit Airlines promotes flights that cost as a little as $9! But to qualify you have to join its $9 club, which costs around 60 bucks, and you also may be subject to a lot of additional fees."
And those additional fees could include up to $45 dollars for each piece of checked luggage, up to $40 dollars per carry-on, and one to $199 dollars for a reserved seat.
Tod says, "Now there are ways to get a great deal on a flight. Ideally, you want to book in advance, and never within two weeks of travel."
And take advantage of alerts that many airlines and travel sites let you set up to track fares. And time your purchase!
Tod explains, "Experts tell us there really is a best time to book. And that's at 3 PM Eastern Standard Time on a Tuesday. Believe it or not, that's when the greatest number of discount seats hit the market."
Other money-saving moves - Consumer Reports says don't skip looking at airline sites in addition to Expedia, Kayak, and Priceline. And don't assume discount carriers are the cheapest.
Major carriers can't afford to be more expensive than low-price operators because that lands them a lower listing in search-engine results.