I've seen a few social media sites before, and HN's upvote button looks how I expect an upvote button to look, and it's positioned where I expect an upvote button to be (next to a corresponding downvote button). Most importantly, it only activates with a mouse-click, which is the conventional way for a user to request some kind of state-change on the web.

By contrast, the kudos widget looks like nothing in particular, its location doesn't correspond to any convention I'm aware of, and mild curiosity (mouseover) is taken to mean enthusiastic support.

To me, the kudos widget makes me feel like somebody took advantage of me in an unguarded moment and stole a dollar. It's not much, in the grand scheme of things, but rubs me the wrong way.

Yeah, but

1) there's no down-kudo, and 2) kudos are mysterious, what's a kudo, and then SURPRISE, it's a 0-click rollover vote.

I find kudos deceptive for both those reasons. That's not what subtle should mean.

Every now and then someone will complain about it, usually after fat fingering on an iPhone.