Cockroaches
Cockroaches know how to find food. That means you have to be extra careful with crumbs and spills. Storing food in sealed containers helps, too. Here's where you have to be delicate: if the apartment upstairs or the row house next door is not up to your standards of cleanliness, you could have cockroaches anyway. Talk to your neighbors - tactfully - about working together to fight cockroaches.
