Cockroach
A cockroach is something you would rather hide coming into view, so it stands for distaste. Even so, traditional reading sometimes took swarming insects as wealth attaching itself, and did not read it as purely ill-omened. Catching or driving them out is a good omen of clearing an old problem, while their appearing again and again signals that deferred work has piled up. If your home genuinely bothers you, take it as a prompt to clean.
A cockroach is unpleasant simply to look at, and the discomfort is what stays with you after the dream. Yet tradition also read a place swarming with insects as money taking hold. How many you saw, where you saw them, and how you felt on waking are what divide the reading.
Readings by Situation
Catching or driving them out
A good omen of clearing an old problem. Tradition read driving pests out as reducing harm. Feeling relieved reads more strongly still.
They keep appearing
A sign that deferred work has piled up. If they return after you thought them gone, read it as a call to fix the root. Writing out what you deferred cuts it down to size.
Seeing insects swarming
Some traditional readings took a mass of insects as wealth attaching itself instead. If it felt deeply unpleasant, though, it also reads as work you would rather not take on. The feeling that stayed with you is the surer guide here.
Fleeing in alarm
A sign that there is something you would rather not face. It is not a forecast of real danger. Read it as a call to look once rather than to avoid.
A cockroach dream does not forecast a real hygiene problem. It is a scene drawn by having something you would rather hide. Whatever felt most distasteful tells you which of the things you have put off should come out first.