You pays yer money and you takes yer chances.
A few, like Ol' Yeller, WERE your best friend, then they go totally rabid.
Now obviously there's some clues going in, in hindsight anyway, as to how she might act ten, twenty years down the line. But seems like lots of guys get totally blindsided.
I figure just plain ol' luck has a lot to do with it.
Birdwatcher