Beside the skull incident the guy in the other reply mentioned, we had for example:

DRM from Game Maker 6 and 7, made the software refuse to launch entirely sometimes, it was specially worse when other products with the same DRM were installed (interestingly, the other products worked fine... I believe GM implementation of the DRM that was particularly broken).

Also the forums frequently had people complaining of the thing losing its registration, or ask for the serial over and over and over again, and so on.

My own story: I decided to make my university final project with Game Maker.

I bought 3 copies as needed for the team.

Then one of them stopped working on my own machine, since I was the lead programmer, that was a problem... I started interacting with GM support team over it, they were rude, and not interested at all in fixing it.

Then I complained on the forum, and my posts were deleted.

Then I searched around on internet, and found out the past horror stories about YoyoGames and how much people used cracked GM even after buying it because of all its issues...

I got curious, and downloaded a cracked copy, and YAY! It worked super fine (eventually I delivered my project to the university using the cracked copy, my dispute with Yoyo only finished after I delivered the project, when I was trying to make another game then, and decided in the end to switch to Novashell).

I then told support it was their DRM fault, their reply was: "It is not... And if it is, complain to Softwrap (DRM vendor)"

Then I told them that the cracked copy worked, and asked them for a official no-DRM version.

Their reply was: "You are a filthy pirate asshole" (or something like that) and they closed all my support tickets (even ones that had nothing to do with the DRM issue).

I got extremely upset, and posted the whole story on their forums, screenshots and all...

Then two bizarre things happened:

Although SOME users got outraged too, most of them embarked into a sort of fanatic fanboism and started to spout lots of random crap, trying to offend me (and any other user that was outraged by my story), and throwing weird defenses... Mind you, most of these were users of the free version (some probably used cracked versions themselves, without paying... I paid for 3 copies, remember that).

Then they deleted my post again... That was expected. What I did NOT expected, was that they "stealthbanned" me, instead of banning me (something that would tell all other users I was banned), they just removed all my permissions, and kept doing that to any account I created... As soon I logged in the forums (with any account), I would get "permission denied" and could not see even the front page, or log-off, but when I visited my past posts as a guest, they were there like if nothing happened, like if I was never punished.

Sad with the whole situation, specially hearing that Mark Overmars (GM original creator) was a nice person, I e-mailed him.

His reply (I am copying and pasting from my g-mail)

"I am sorry but I am completely not involved in this process. I can only recommend that you ask nicely and apologize for using a cracked version. Hopefully that helps.

Mark

______________________________________________
prof. dr. Mark H. Overmars
Institute of Information and Computing Sciences, Utrecht University"

Later Yoyo pulled (against other people... I had already left, for obvious reasons) other funny stuff, like their first iOS Gamemaker they did some backtracking on promises and did some unexpected stuff, and charged a "tax" too (I don't remember the exact numbers, but if you sold something for 1 USD at iTunes, you paid 30 cents to apple, and more 30 cents to Yoyo, also the game had to be on their account, so they got all download numbers and whatnot, not benefiting you of cross purchases).

To me it does not matter that the programmers are nice, or that the thing is well programmed, or that they removed (after so much problems) their DRM, what matters is that Yoyo games is a company that has no respect for its costumers.