Great Virtue vs. Cheap Virtue

Glaring and great injustice elicits glaring and great virtue - but also, alas, glaring and cheap virtue.

How can you distinguish between them? I have a rule of thumb.

One does more to improve the condition of the injustice than the condition of the person speaking out or taking action against it. The other does the opposite.

Do you agree? Have you ever caught yourself on the wrong side of that line?