As a guitar instructor, a lot of people are extremely surprised after they discover how I learned to play the guitar. I am a living example and proof of the fact that it is possible to learn to play the guitar, without needing a private guitar teacher. If I could do it, anybody can, all it takes is dedication and work, and you'll be playing easy guitar songs in no time at all.
I have been playing the guitar for roughly 15 years now, and true, I did possess a musical background already, because I already played the piano as well as the trumpet. Even so, the guitar is completely unique, so even though I already knew how to read music, I had to train myself the guitar essentially from scratch. Plus it was not as easy back than, as it is today.
The Internet offers an overwhelming quantity of info on any topic, as well as guitar lessons. Lots of newbie guitar players type the phrase guitar instruction into Bing or Yahoo, and don't know how to proceed with the 10 million results the search engines provide them with. This is really a negative part of learning guitar on the internet, since beginners will usually go from one web page to the next, without actually learning anything.