I just read the post where Yakko votes Ciato...
He pretty much voted her out of process of elimination, little else. It was a "there really isn't much to go on, she seems the most suspicious, even if its very minor, but that's about it."
Again, read that post; he's mostly finding people with neutral or town reads. Ciato vs. Alex was the thing he commented on regarding the two, saying Ciato felt a bit scummier than Alex, and he actually agreed with from where Alex was coming from regarding his defense.
Don't really see this leading to much honestly. If Yakko had started a Ciato train or was the first to bring a case against Ciato, I might agree...but that wasn't the case. Alex started it with what felt like a flavored up OMGUS Vote on Ciato, this lead to Ciato overreacting a bit, which in turn can make things a bit suspicious. Alex presented his point several times, Yakko pretty much just was agreeing to it, at least favoring them over the points against Alex.
Yes, he hammered Alex in the end, but it was similar to my hammering Smodge; wasn't fond of the action, but we needed to hammer someone. Alex wasn't going to suicide, the other two were seemingly not coming back (or outright said they weren't? Can't remember), so Yakko was the deciding factor. Hammering Alex cause we need to Lynch Someone feels like it means little frankly.
Also, Yakko was on Alex's side of the argument, to put it one way. If he was Scum, I don't think he'd try to defend Alex. Alex was too easy a target for scum to pass up in terms of a lynch. He's dead set on killing Smodge the entire game, Smodge flips up town when finally lynched, then his next action is, again, attacking the one person who tried to question his tunnel vision, right when the day starts. This is something Scum would try to take full advantage of, frankly. And then consider its Alex, someone who many consider a good player...yeah. Furthermore, leaves them with a nightkill open as Alex is often a lightning rod to these things, they don't have to worry about wasting it on him (though, seems like they were predictable and Andrew stopped them anyway.)
So yeah, for now, I just...don't see the argument for Yakko. Mind, I don't have a good read on him as is, but don't get a scum feeling as of now.