Chris,
I have three original Agfa's, Isolette 1, 5, and a Ventura, none leak. But have seen a couple in disastrous condition. They had come from the US southeast. Lots of high humidity down there, which I suspect degrades the bellows material. I live in the US southwest, even our mountains are dry and arid, hence powdery snowfall. I've found if a camera was brought here early on, it's chances of survival were much greater, nicer bellows etc..
2bits