Yeah, shwag is usually compressed and smells like dirt, amonia, hay, or has not much of a smell at all. Usually brown instead of green. Usually stemmy and seedy too. Just being compressed doesn't necessarily means its crappy though, neither does being brown or having some stems and seeds. Smell usually works though. If it doesn't have much smell, breaking open a bud will usually give you an idea of the true smell. I have had some good smoke that was compressed but it almost always had a good smell.