I've seen this in the helicopter industry. Let me fly your shiny gas turbine choppers for free please Mr/Mrs AOC holder!
Once they had some experience they would then say, oh, I've got experience now, how about paying me to do the same job? Never happened. The accountants just found the next mug to fly for nothing and they were 'let go'.
When they moved off looking for their next job with their fist full of hours usually the operator would give us a ring and ask how they were. Nothing was ever embellished but most operators were rightly skeptical when they were told they were let go at the end of their 'paid for by themselves' hour building.
Thankfully those dark days of 'fly for free' seem to be over in the helicopter industry (going back to the 90's now) and I would hate to see them in the fixed wing world as well. Getting ahead is one thing but trashing the already diminished T's & C's for newbies is, in my opinion, despicable.