One of the things which bothers me is that, with the explosion of interest in all aspects of Yoga, there has been a concomitant dilution/muddying of its original teachings by Self-styled, New-Age, Half-baked gurus and plain old Charlatans. They simply lack the knowledge, which is unforgivable when you realize that the original sources are just a "google search" away.

For people interested in the Original sources, i highly recommend starting with; Roots of Yoga by James Mallinson and Mark Singleton to know the primary sources and then actually reading them.