Well, Carrow hasn't pounced yet so it's a good thing I'm not in Divination, I guess.

We've done a little blood magic in Dark Arts class but we had to use our own blood. That limits things rather a lot. Miss Professor Carrow talked a bit about how a wizard or witch's blood is far better in this sort of spell than muggle blood (but any human blood will work a good deal better than animal blood). You know what's interesting, I'm sure Carrow would die before he said he thought you were a real wizard, that your blood was basically the same as his -- but that's why he wanted YOUR blood. Because it's wizard's blood, it's powerful.

And for that matter they'll say that muggles are the same as animals but it's pretty obvious they know they're not.