I was thrown strait into the musical deep end in my first year of college by a group of people who had an average 7 or 8 extra years of living over me, so by the time I owned my first system, I ended up with mostly decent stuff.
Probably the worst album I bought was Season of the Witch, Seven Stills and John Mayall. Great artists, but the album was cut from a late night, drug and alcahol induced jam session that someone thought they should sell. The title track was good. The rest was embarassing.
I also owned a couple of Nazareth albums that I could never listen to again.