Quote:
Curious if anybody has any best practices for identifying stamps that are just worthless in quality for purging a collection with many duplicates
Seems like the OP is not asking what to do with his duplicates, but rather how to identify which ones are worthless? Is that correct?
There are standard ways to grade your stamp in terms of intact perfs, well centered, etc. Just look in the front of a Scott (or other) catalog.
In terms of cancelations, go by what looks good to you. Generally, light, clear cancelations are preferred (to those who collect used stamps; some prefer only unused stamps).
If I have a duplicate of a particular stamp, I usually compare the two and keep the one that
I think is more attractive (however that is defined) and the other goes in my duplicate envelope.