I think that is a bit of an urban myth that they go for the face/neck. When they are cornered, they are looking to get out. They see the best means of getting out to go up and over - hence they aim towards the upper body.
I had a live one in my living room last year (courtesy of my cat who brought it in alive). I nearly wet myself when I saw it cowering in the corner of the room. Mind you, it wasn't in great shape - having been mauled by the cat and then left upstairs in the living room all day (where there is no water and rats need to drink every hour else they quickly dehydrate). I went and got the other cat (the killer, rather than the playboy) and poked it with my walking stick to liven it up a bit and she finished it off for me. Still made me heave when I scooped it up to dispose of it.