Regarding bad habits, I recall surfing YouTube one day visiting various sites for playing tips.
I came upon this one site where the hook line was for a particular tune that I liked and this guy was going to show everyone how to play the riffs.
OK, so I click on the video and he starts to explain the various chords and such and then starts his demonstration by showing everyone how to play the opening chord. He began his demonstration by saying that the first thing to do was to fret the 5th and 6th string with your thumb and then...
Record scratch!!!
Apparently this "teacher" had Jimi Hendrix fingers and whatever he does may work for him but for mere mortals such as myself with average size hands the
"Two-strings-with-the-thumb" bit just ain't happening!
This pointed out the difference between true teachers and showoffs -- or at least people who don't realize that other folks may not have hands the size of shovels and for whom certain "positions" may prove to be impossible.
This is yet another reason to respect Griff's approach to teaching because he basically teaches in a more traditional or even "classical" manner which allows almost everyone with functional hands of any size to play guitar. Things like fingertip muting, palm muting and proper finger placement are all staples of good teaching. And yes, from time to time Griff may point out that what he refers to as a "Rock Thumb" or single-finger chords will work just fine if one has the facility and comfort in doing so. But he always starts off by demonstrating a more correct way to do something and then offers some alternative ways of doing it and lets the individual decide what works best for them.
THAT's the way to do it!
Before I found BGU, I was doing many of the things Griff teaches (out of necessity) and when I found BGU I was pleasantly surprised to find that I wasn't doing anything wrong but rather I was doing what worked for me and having that confirmed by him gave me a shot of confidence and reassured me that I was not only on the right track but also that technique isn't carved in stone and that there are often many ways to get to the same destination.
So whether one can play chords spanning six or seven frets or if they choose to use a pinky instead of a ring-finger or if you're someone like me who can't palm a basketball (I even have trouble with volleyballs) and thus do not possess the "wingspan" of others doesn't really matter as long as whatever you're doing in whatever way you're doing it produces the result you're looking for.