I agree with James and the ME staff that Spike was evil. I don't agree that James and ME are the ones responsible for not conveying that clearly to the audience. Yes, James did play Spike with soul prior to actually regaining it. He had to, just as the writers had to create scenes that allowed James to convey Spike's humanity. In order for a character to be gripping - to hold the audiences attention - you have to care about them, or at least be intrigued by them. Would six seasons of just plain evil Spike have done that? Would he have lasted six seasons if all we saw was a demon plotting to kill Buffy and the gang?
The demon was always present exerting a certain amount of control. In season two, Spike only sided with Buffy to save his 'happy meals' and, in a misguided attempt, to win back his precious Drusilla. In season 3 we see Spike has not changed - threatening to kill Xander and menacing Willow to achieve his goal. Now, in season 4 the essence of what Spike was may have become less clear as he was forced into the role of comic relief. But underneath the quips and puns was a seething resentment and secret pack with Adam to destroy the Scoobies. Only when he realized his own unlife was in danger did he join the side of good to save his own ass.
Where things get muddled is in season 5. Yep, Spike loves Buffy, but in a very selfish way. Tara alludes to why it can't work in her Quasimodo discussion with Buffy and Willow. And chaining Buffy up, threatening her to prove his love? This always harkened back to 'Lovers Walk' for me. Spike announcing he was off to find Dru to tie her up and torture her until she loved him again. Considering how desperate Spike had become, had not Harmony interrupted or Dru gotten loose, who's to say how far Spike would have taken things with Buffy?
I know a lot of fans blame season 6 for the confusion regarding Spike. That the AR was simply thrown in there to fix the writers mistakes and prove how evil Spike still was. I've never agreed with this take. Yes, it was disturbing, but I never felt it was something that was beyond Spike. Especially when considering where Spike was emotionally in that moment combined with a history of physical abuse towards each other. James is correct, the act itself is evil and shows what Spike was still capable of doing. What hasn't been addressed, is that it is also the moment when William's humanity is brought forth. Confronted by despair, disgust, and contempt for himself, he sets out on a journey to regain his soul.
The inherent evilness of Spike was always there beneath the surface waiting for the opportunity to be released. The chip did force Spike to suppress darker aspects of his being, thus allowing pieces of his former nature to reveal itself. Eventually Spike was lulled into a belief that he could overcome his nature on his own. The AR forced him to see this was not so. And while ME has showed that souls do not always equate with good, we have seen that Spike was a good man before being turned. Regaining his soul provided Spike with the moral center that he had lost. Whereas in season 5 and 6 most of his good deeds were for Buffy's sake alone, in season 7 he did the right thing because it was the right thing.
If the writers screwed up anywhere in confusing the issue, I would say it was in 'Intervention'. An episode that managed to convey both how low Spike could go as well as what heights of greatness he could achieve. Spike was willing to accept death rather than reveal Dawn to be the key - a truly selfless act. It was then that it became more difficult to just view Spike as the Big Bad. Without 'Intervention' ME may not have had to remind viewers of what Spike was still capable of doing and why he was not to be considered the hero. On the other hand, I've always believed that ME wanted to tell a story of redemption and without 'Intervention' Spike would not have taken his first steps along that path. Up until that point we knew what Spike was but not who he was yet capable of becoming.
James has always revealed remnants of Spike's soul or his humanity or whatever you choose to call it. I don't see that as a mistake on either James part or the writers. Without that he would have been no more then the disposable villain he was originally intended to be. ME wouldn't have been provided with the epic character arc. And we wouldn't have benefited from watching such a great story unfold.