much of which is substandard and you want to learn from it!
Just because some of the information isn't great, doesn't mean there's nothing useful out there. You just have to find it, and judge what's good and what isn't.
For example, I judged that the tutorial on this particular website was pretty good; so I learnt from it. Other tutorials I found on the internet (such as one that claims to teach you C++ in 21 days) didn't look as good, so I ignored them.
Ok. Are you in any better position to judge who is a good teacher or not? No, you aren't.
Not quite the same thing. What we have been discussing is the quality of the information not the quality of the teacher.
With yourself as the teach, you have to decide what to learn in what order and from what source. If you find a good source of information (accurate, well written,and consistent) the learning process is made much easier. Not all information on the net meets a good standard.
With a bad teacher, if they have a good source, it is still possible to learn well. But then again, you may not understand the path that they are taking you down and think they are a bad teacher because of it.