Novice-Intermediate tea drinker (3 years serious tea drinking). Mostly sheng pu-erh, some oolong, the occasional black western style.
Try to avoid nonsense, hyperbole, and reading too many flavours into a tea. Red wine tastes like fermented grapes most of the time, tea tastes like boiled leaves most of the time. The question is: are they good fermented grapes, are they good boiled leaves?
0-25: Throw it out! Not even worth drinking at any price and cannot be gifted in good conscience.
25-50: Would not buy (again), unlikely to drink. Might be worth gifting to friends/family with lower standards (and western brewing only).
50-60: Would not buy (again), just drinkable.
60-70: Would consider buying again at a good price. Interesting or good enough to drink once in a while. Also, teas which I do not personally like but which I can see the objective merits of and might please others.
70-80: Would buy again, daily drinkers.
80-90: Definitely buy, excellent quality.
90-100: Buy at any price, the best of the best (I have never drunk anything this good…).