I've personally "bounced off" of some games because they didn't reflect the playstyle they were marketted as having, and/or the way they were pitched by the GM. Thus I didn't engage the games properly due to mismatched expectations, some outside of my control.
Sure, players might be going in with incorrect assumptions (God knows that I've experienced this) but I've met DMs who also didn't quite properly grasp the system either...
For example, about a year ago I joined a brand new group with a GM who pitched a particular non-d20 game to us, insisting that it was "faster and more action-oriented than D&D". He also promised that fights would be shorter and more exciting and that characters "roles / classes" would be more compelling, with more intuitive rules that allow for more stunts.
It... didn't quite meet up to that at all. It wasn't all that fun, but it turned out that it wasn't the system's fault: he was running a specific setting module... with pre-made "Core" characters. So my "Rogue" didn't have any classic typical Rogue abilities. Cool stunts were discouragingly difficult to accomplish (and our skillsets weren't really the greatest).
At one point the GM, seeing my character being quite ineffectual in the combat scenes, reminded me that I should really be taking advantage of the Rogue's abilities like sneak attack and other maneuvers to better engage with the action aspects of the game. However I showed him the pre-made character he printed out for me, which had none of those abilities, in fact, the strongest abilities were related to connecting with underworld city contacts (the adventure was entirely out in the wilderness) and acrobatics (none of the fights had any cool terrain to exploit). There was a pause, he looked around the table, shrugged and we moved on.
A very specific anecdote, but I wanted to explain how it isn't just the players' fault when player germs vs. game terms are mismatched.