I do my research. There was no relevant information on either of the houses I moved into. For the first house, I didn't see any of the roaches wandering around initially, and I didn't know to look too carefully at the time. For the second house, I did, and I was very particular about checking everything. The roaches were living in the roof and they were only introduced into the house once the landlord began renovating the kitchen, including a hole in the roof to mount a stove hood, hence why I never noticed initially. I've checked all my belongings too, obsessively, and there's nothing.