I will sacrifice a full cigar to the dissection gods every once in a while just for educational purposes, and sometimes unroll a 1/2 smoked cigar for shits and grins, but usually I just toss them once they are dead.

I usually look for the burn characteristics. A sharp point in the center of the ash usually indicates that the roller used a full slower burning leaf in the center of the filler. Lots of stems in the foot before you light it could indicate chopped up floor sweepings.