Are the Buddhist sutras 100% verified if applied in life? I remember my teacher mentioned this in class : 


  "Do not believe in anything simply because you have heard it. Do not
  believe in anything simply because it is spoken and rumoured by many.
  Do not believe in anything simply because it is found written in your
  religious books. Do not believe in anything merely on the authority of
  your teachers and elders. Do not believe in traditions because they
  have been handed down for many generations. But after observation and
  analysis, when you find that anything agrees with reason and is
  conducive to the good and benefit of one and all, then accept it and
  live up to it."


Does that mean that the sutras are 100% correct if I follow them? because it is very confusing, or according to what siddartha mentioned, I can't even trust the sutras when he says do not believe?
In the real quote (here), the Buddha emphasized believing in that which: 


"when adopted &amp; carried out, does not lead to harm &amp; to suffering"
and
"when adopted &amp; carried out, leads to welfare &amp; to happiness".


Therefore, you can trust the majority of the sutras because the majority (but not all) are about giving up harm &amp; suffering and cultivating welfare &amp; happiness. 

The Buddha wanted his followers to investigate &amp; realise the teachings for themselves.