Not one but two no less, apparently. If you weren't emotionally invested in either Willow or Tara, you more or less saw it coming a mile away. The same thing with Spike and his arc - people who were not emotionally invested (either for or against the character) saw the arc fairly clearly.

Goes back to my central point - emotional investment blinds you to the plot.
Except for the whole taking out the chip or getting a soul arc - that confused everybody including the actor.