We all know that airlines have come to rely on extra fees to support their business model. With results like today's quarterly earnings -- with Southwest ( LUV - Get Report) shares dropping 50,000 feet -- they have to. It started with the first $15 charge for checked bags what seems like a lifetime ago, but was actually just back in 2008 for major carriers. It has grown to encompass just about every aspect of flying. When it comes to buying airplane tickets, passengers are notoriously price sensitive. We look for two things when it comes to booking a fare: flight duration and price, and that's pretty much it. We may grumble about the add-ons and extra fees they smack us with at the gate, but it hasn't changed our purchasing patterns yet. 
 
Here are 5 crafty ways airlines rip you off