This is a great question. I think most gamers go out of there way to research the games they purchase, but even so duds still will appear somewhere in a disk tray more often than they anticipate.

While I stayed away from the notoriously broken, like Operation Darkness and Spiderman, I did have the "opportunity" to borrow Star Wars: The Force Unleashed. I felt critics were very kind to the amazing short comings to Force Unleashed.

None of the new technologies, bio-mechanical a.i., the realistic environmental manipulation, had no real impact on gameplay. It did'nt help that with those new technologies came a flood of new problems. The engine itself already had issues. The level set pieces were gorgous, but the level design was insanely boring.

Then there's the now classic star destroyer scene, which is perhaps the worst single gaming experience I have ever experienced this generation. After seeing the teaser trailer and witnessing the jaw dropping cutscene of a jedi pulling down a stardestroyer I asked my friend what it was like in the game. His response is a pretty universally accepted account of the sequence:

"It's like they went out of thier way and made the worst mini game ever." I laughed when he said that. I proceded to correct him. "It can't be that absolute! C'mon! There's worst mechanics put in games before!"

Then I played it. Good lord it's terrible.

Granted even with broken Devil May Cry style combat and technical problems galore, I really do throw my hats off to guys for being able to get through the likes of SpiderMan and especially Operation Heart of Darkness. In fact I consider my worst experience incredibly lucky. I've heard horror stories from both titles.

I described the game with more detail here, but Operation Darkness is just abysmal.  I think it's the first strategy RPG I've played that I could honestly classify as broken.

Although I did enjoy this game, it took a lot of forgiveness and frustration from me to see it through to the end. The new combat system was a definite improvement and the story was good enough to hold my interest, but the game had so many bugs and performance issues. Enemies would disappear mid-combo, the anchor point swinging wouldn't always anchor to a point, the enemies and missions were horribly repetitive, and the frame rate dipped into the teens at the slightest provocation. The game feels like it wasn't play tested, which is a shame because controlling Spider-Man is as fun as ever and there is a lot of potential in there... but you'd be hard pressed to find it.