There's two types of roaches. The little ones you see in northern states and the big palmetto bugs you see in the south. While the big ones are freaky, seeing one in your house isn't necessarily the worst thing ever. Even the nicest, cleanest houses in Florida will get the occasional palmetto bug. Now, the little German roaches? That's another story. If you see one, that means you got a thousand somewhere in your house. I had an ex girlfriend who had birds and those little fuggers had infested one of the bird cages. We had to throw out the cage and bomb the entire house to get rid of the roaches.
As for rats, the only place I've ever lived that had issues with them was when I lived on the water. Rats down here like to live near the water and if you've got a house on the water, there's a good chance they're getting inside your walls or roof. Especially in the winter when it gets cool.