"The Grateful Dead sound like crap!"

If you believe this, then, as Carlos Santana said, you haven't raised your consciousness to a point where you can really hear them.  That's okay.  Many of us remember a time when we thought their music sounded way too flawed to deal with.  This passes...trust me. For many, the Grateful Dead are most certainly an acquired taste.  Sure, you'll meet Deadheads who claim to have loved the Dead upon first listen; but I think they are in the minority.  Most of us come to the Dead accustomed to hearing a different sort of music -- over-produced, over-polished, near-perfect stuff that has commercial appeal in spades.  So the Dead require a shift in one's expectations; and perhaps a paradigm shift as to what constitutes 'good' music.  You need to complete the square with the Dead, so to speak.  You have to 'hear' what they are going after; dig into the tapestry that is their sound; isolate individual players in the mix, and open yourself to an extremely eclectic musical experience.  Don't like what they're playing?  ...Wait a couple of seconds.