Except they didn't use Muggle blood. It was chicken blood. The only person to have ever even been bitten by the basilisk, as reported in the books, was Harry.

I know. I wasn't trying to abide strictly by what the book said, though. By realistic, I had meant that the message would look more suspicious with blood. Thanks for the information, jjamesgordon.

No problemo. Don't know who thumbed you down, but I brought you back to neutral. It would look indeed more believable in any sort of red medium. There's a girl at my university who likes to write the message on the mirrors with lipstick.

You did that? For me? That's the nicest thing someone has done via internets for me all day. And a Thumbs Up to that girl at your University. I'm gonna have to try that.