a lot of "pet fancy" magazines are only published quarterly or otherwise rarely, etc, and they know that you're probably going to buy *one* and stick with it for the life of your ratties (example: the two books on hamsters that my dad has had since the 1970s, lol), so the mags usually will put in an article on all the major sicknesses of that animal or breed, and then a few on shows or competitions, and then a few articles on "oh look how cute they can be!".
and besides, all animals have *a lot* of possible sicknesses, and very few end up with many of them at all. most rats aren't going to be sickly their whole lives, or if they are, they don't usually get *everything* that a rat is prone to getting (like you'll have a tumor-factory for a rat, but probably not a tumor-factory that also has bad lungs and skin, etc.), but for educational purposes they have to mention all of the potentials. i would try to adopt from a breeder as all breeders breed with the ultimate goal of health and temperment in mind, to greatly reduce the chances of getting a sickly rat.
