Good weed is usually a little moist and sticky, has a fresh green color to it than pale green, yellow or brown. Brown weed is the worst and must totally be avoided. It has a nice and fresh smell to it while bad weed usually smells musty and like a room that has been shut for years. Effect wise, good quality weed gets you relaxed or focused, unleashes creative thoughts. Smoking bad weed will give you anxiety and panic, and sometimes make you very drowsy. Lastly always check for molds. Good weed never has molds.