OK, so British Airways isnt the World's Favourite Airline huh? Well...in that case.......
Is EasyJet proven to be the Web's Favourite Airline, no, well they better stop using that line then. Is Ryanair, The Low Cost Airline, hmmm, well theyre not the only low cost airline, so they better stop using that......Delta, does everyone there really Love to Fly and do they always Show it, hmmm, what happens when it doesnt show? They better stop using that line. American, so you're the American State at 35000 feet, hmmm, what happens when you fly at 30000 feet, what state are you in then? Get rid of it! United, well you were the Friendly Skies, and then you were Rising, what happens on cloudy days or during descent? Nup, cant claim either of those things....they gotta go, sorry. KLM, so youre the Reliable Airline, huh? So you have the best ontime record in the world? no? Well, you guessed it, you cant use that line then!
......Anyways, you get the point
Marketing slogan's are just that. Pure marketing. The are there to stir emotions and aid brand recognition - they're not there to be taken literally.
p.s. I know some of the above mentioned slogans are a bit out of date, but I was trying to prove a point, so please dont post a million things like "thats not their slogan anymore"