I don't buy bad games ;) No, seriously. I don't know how we (my best mate and myself) ended up with either Tenchu or Battle Arena Toshiden (Tenchu we just didn't seem to play much, and BAT we couldn't get the hang of).
Of games I've bought on my lonesome, I didn't like Myst the most. Partly because it seemed to be far too hard, and I gave up really early on and haven't been back since. Could be just me though.