When i first started playing bouzouki i had some books with partitoures etc.I have noticed many mistakes on many songs,many of these books are very very inaccurate.Of course you can find sheet music which is written with big attention and without mistakes but you have to search a lot.As an advice to many new bouzouki players i will say : ''trust you ear''!
You are of course right, but it is not bad to have also some other material for learning. Without book I would not know how to play chords on baglamas, so I am glad that there exists something like this especially if you live far from people which could teach you this (I live in Czech Republic) and you are not able to learn it alone without any help - just with your ear.
It is truth that I found some mistakes in some books which I bought, but then I was happy that I am on level when I can notice mistakes without any problem.
Discovering mistakes in books is also practising your ear.