Because they eat your food, shlt on your dishes, walls and furniture, breed by the thousands within a week and most of all, THEY DON'T PAY RENT!
Even though I love things that are usually misunderstood.. I just cant get over creepy crawlies.. Cockroaches can hiss (it scares me and I know they are mad! lol) and have been displayed as "dirty"..
They're pretty disgusting.
They spread filth and disease.
They smell, they carry disease, they have eaten the finger prints off of babies, the only thing I see as worse is Fire Ants
Because they're full of disease. They like to crawl around in garbage cans and hide where the grime and dusty food crumbs are.