Mine is surprisingly amazing at picking out partial dog parts. What's weird is that the interface (as far as I can tell) has no button for "no this is not a dog". Same thing for face clustering, where I have like two (or more) clusters of certain people.
It's random enough, a blurry cat, head down, in the night can be tagged properly, while a nice walking cat in normal daylight conditions but behind open window blind won't be flagged. Not that surprising though.
Mine too. I search for dog, and two photos have a dog in them, 4 photos have a cat, and 1 has no cats or dogs, just a baby.
CAPTCHA - Cat-based Automated Public Turing test to tell Computers and Humans Apart