I think everyone's hypothesis on the scent issue has something to be said for it. There should be no consensus or agreement, given the scant info in the manga, which points in every direction.
Taking a tip from the Witcher series, perhaps Yoma is a microbe infection. In Scene 33, Clare tells Lucky to hold on to her, tight as possible, before she escapes Ophelia. Clare has her blood all over her body, which Lucky is exposed to.
If a microbe is the agent for creating Yoma, there must be a variety of strains. The microbe that Teresa and Clare carry would produce a scent particular to that strain.
Lucky's exposure at Gonal isn't enough to turn him into a Yoma. The infection on his skin would be a benign one---just enough to "carry" Clare's (and Teresa's!) scent.
I personally don't believe Yagi intended any of the above---it's all imaginary like the series itself---but I couldn't resist :-)
Last edited by jamie95403; March 25, 2011 at 05:23 AM.
Teresa was a high factor one psychopath with a strong code of internal rules, Priscilla realised that Teresa would have violated those rules by killing the vulnerable which is something that Priscilla used to her advantage, turning Teresa's own gut instincts against her by acting like a child at the correct moment then accidentally-on-purpose awakening to take her by surprise.