No one can agree on what this guy should have done after he bought a guitar for less than 10% of it's true value. This is one of those posts from r/AmItheA**hole that make a great read. That's because even after reading this dude's story , plus the update, we still can't decide who was in the wrong in this situation. As the OP, u/fhdksTHROWAWAY wrote, their wife's coworker was selling a guitar. As an avid guitar player for decades, the OP was thrilled, and decided to help this guy out by buying…