there is no way to know honestly. it could grow some serious dank if grown properly (i.e. keeping the males out to prevent females from being pollinated, good lighting, good ferts, conditions, etc.). i know it's not the answer you're looking for, but there is just no good answer to your question short of just growing it. it could be the best shit ever, it could be shitty. my suggestion: don't grow unknown bag seeds...instead order some seeds of a known strain online and grow the best shit you've ever smoked.
Well taken care of mid seeds from a bag will turn out to be better than the weed they came from. No guarantee that it will be some awesome strain, but the weed will definitely be better than before.
What he said. Pretty much all the bagseed plants I grew were just as good as the "real" strains I ordered.
