Strangely enough, I use this sticky for most of the links for learning how to do new things. scirra.com/forum/topic45416.html
They are not necessarily tutorials, but good links to working projects.
But yeah, a good rating for all new tutorials and old ones should have a ratings system of some kind. I know their team is small, but I do think this will help newcomers learn better and will have fewer questions.
If the author updates the tutorial to make it better, the bad ratings would still be there, correct?
Maybe, tags of "needs improvements", "broken links" or "great tutorial".