I am in no way singling you out when I say this, but that statement has never really made a whole lot of sense to me, no matter how many times that I hear it. We are expected to forgive Angel for everything that he has ever done when he has no soul, we even have a separate name for him when he is in that condition, and yet we can't give Spike the same consideration. If Angel can have an "evil twin brother" named Angelus on whom we can heap all of the bad things that he does, why can't we give Spike the same consideration? All of the good things that Spike did before he regained his soul, the pain that he endured rather than betray Buffy and her family, the times when he covered Buffy's back in battle, his fulfillment to a dead girl whom he had every reason to believe that he would never see again in this world or any other, even the assisting in literally saving the world, are all ignored because of a single mistake that Buffy, herself, forgave and put behind her. No "evil twin brother" for Spike. Every crime, sin, and act of mayhem that he has ever perpetrated since clawing his way out of the grave, is piled on him and never forgotten.
At the very best, the good things that soulless Spike has ever done are simply brushed aside with the excuse, "Well, yes, he did do all of those things, but he only did them to impress Buffy," or, as Angel so eloquently put it, "to get in a girl's pants." Okay, granted, Spike was motivated by the need or desire to please and impress Buffy, at least at first, but I will submit to you that EVERYONE, in the beginning, does the "right" thing in order to impress someone, usually their parents, long before they ever have any real concept of good and evil, or right or wrong. And that was exactly what Spike was doing, and for that exact same reason. He wanted to please Buffy because, even without a soul, he loved her, and he wanted to earn her love in return. I somehow find it extremely hard to imagine Angel, minus soul, ever doing anything even vaguely similar to that.
So let's at least cut Spike the same slack that we do Angel. Neither man should be held responsible for anything that they did prior to regaining their soul, or both should. Level that playing field, and it might just be that Spike is a better man than Angel ever will be. Or not. But at least give the guy the simple courtesy if judging both him and Angel by the same standards.