Guitarists are not known for being very good readers for their instrument. Let alone being good at sight reading!
Why is that? Well, it's to do with a few things that I could list:
- self taught - unorthodox learning curve
- It's not very 'rock n roll' - a question of attitude
- No idea how to go about it in a progressive way
- Poor return of investment when the returns on other skills area are more immediate
and so on...
It is true to say that most guitarists are 'self taught'...whatever that means in this day and age - where one is potentially overwhelmed with available information out there (perhaps that is a problem in itself...). But no one is telling a would-be guitarist to find some discipline to become a good reader. Perhaps only the oddly determined or those with a strict guitar teacher would ever end up acquiring these skills to any proficient degree.
Classical Guitar has always had a tradition of reading; and its practitioners usually become good readers. But that is not the norm - certainly not in other forms of popular music.; though Jazz Guitar is often an exception.
Attitude: a lot of guitarists probably think they can get away without it...and I dare say there is some truth in that. But there are benefits to being a good reader nonetheless: it teaches you the fingerboard well; it is a good way to absorb music theory. It also has benefits in song writing and arranging endeavours. So being able to read and write the musician's language is no bad thing.
For sure, there are effective ways of learning how to read for guitar. Personally I often recommend Mel Bay's first publication from around 1945:
This book and its subsequent grades has been and still is a very popular book. Mind you, this is strictly for plectrum style; there are other books that will help you develop sight reading skills for finger style guitar...such as Robert Benedict's...
The final point I'd like to make is this: many a guitarist would argue that there is a poor return on investment on learing to read well for guitar. Afterall, guitarists do not often find themselves in situations where they have to read; unlike ensemble instruments.
Well, that much is true but for reasons already provided, on balance, I think learning to read and write our language is a good thing. Let's face it, if you cannot do it then you are illiterate!