It's worth being skeptical of claims that people are faking disability. For example, there is a common belief that wheelchairs are for people who can't walk, but a lot of wheelchair users can walk, just not necessarily without pain or for long periods. I don't trust airline staff's subjective impressions to be well-informed.

On that note, stories constantly circulate of airlines breaking or losing wheelchairs through improper handling. It seems like wheelchair users dread having to fly because there's a huge risk their mobility device will be destroyed after their flight.