Quick question about shifting towards PWWT

[boogle]

So the Demon's Souls wikkidot says that assisting players in killing bosses as a blue phantom will shift the world tendency towards pure white.
Is this a good way of doing it? Can I effectively farm it by killing myself in the nexus and then going out and killing bosses as a blue phantom? Is that why I see so many bloodstains in the nexus?

Also, if I have already killed a boss in body form, can I still assist someone in killing it when I am in blue phantom?

[Shinikama]

I'm not sure about WT, but I know it changes your Character Tendency.
Still, it can be helpful. Stronger attacks and all that.