Of course, there are some basic guidelines for the classification of tea quality, i.e. hand-picked, semi- or completely hand process and natural authentic fine flavors and tastes are always considered as the best quality.
Price does give you some ideas about the quality that you can expect, but the fundamental principle is being able to tell the authentic vs. aromatic. The question is, exactly how much do you know about tea? No matter what, it is not logical to expect
To certain teas, the presentence of stems is normal, before exclude stems out, should try to clarify which tea types we are talking about.
However, I do think the most important thing for us,
Each person can draw the line about good tea based on her/his own personal preferences in flavors and tastes.
Try to deepen the knowledge by listening to tea instead of floating around.