Nutella. We had read so much about it and then one time while in our home away from home (Moab, UT) we bought a jar and tried it. Thought it was sickeningly sweet and not much else. Gave it to the motel cleaning ladies.
OTOH, I bought a slab of couverture Gianduja (the precursor to Nutella) to use in making chocolates and really enjoyed it.