Do ALL ferrets end up with disease?

My roommate and I have been planning for a while to get a ferret. We have time, money, and space for it. We've also been researching a lot as well. We found a so called "ferret rescue" in our area. When we called, the woman in charge asked if we "even knew anything.about ferrets", and rudely said that "obviously didn't know that ALL ferrets end up with two disease and rarely are healthy." And she continued by saying "dont expect to be the lucky ones whose ferret didn't get one of the disease". We had in fact read about these diseases (one being adrenal I believe), but that it could be prevented with vaccination. so which is true? Is this rude woman correct? Do ALL ferrets get sick?