I don't know how you guys relate terms and grades, but bad weed has a combination of these characteristics:
Stemmy
Seedy
Poorly manicured
Poorly dried
Uncured
Unflushed
Flavorless
Shitty high
Not grown with love

And good stuff has these:
From strains that were bred for flavor/effect, not just yield and ease of manicure
Grown carefully
Dried properly
Cured
Not bricked
Etc...
Get it?