Couldnt have put it better than Slipknot psycho. If the grower is using bought seeds then it has the potential to be very very nice weed. But due to budget, experience, knowledge, equipment, handling and many other things it reflects on the quality.

The best situation is grow your own if you can and have the knowledge, next best is a mate that grows to smoke, next is a grower that smokes but is your dealer and not your mate.

Then there is a mate dealer or friend of a dealer. The worst is someone who offers you weed on the street because they shouldnt have to come you. If they had nice weed and did nice deals then they shouldn't have to look for customers.