I suppose many blattophobes think they're dirty < although they're just as fastidious and self-grooming as their relatives Praying Mantises and termites> or find the way the faster species run alarming < superbly fast reaction times, using the little cerci organs sticking out of their butts to detect any change in air pressure, then legging it so fast their front end lifts off the ground and they skim along propelled only by their hind legs. > Movies such as Creepshow, Bug!, & Damnation Alley probably don't help.
There are pest species, admittedly - ones that hang around houses, having found the way humans keep nice warm houses, with lots of water and food to eat - ie. grease films behind ovens - and not much around to eat *them*, really comfortable.
Over here in Australia, we've got some 450 species, but only 6 pests - all introduced. German, American - aka Palmetto Bugs - and Australian Roaches are pretty much worldwide these days. And both German and Australian Roaches are from Asia, and American Roaches were originally African, anyway.
Then there's all the other genuinely Australian roaches - from the tiny, beautifully veined Ellipsidion Tree Roaches, with their circular babies; the wonderfully camouflaged Onicosoma granicollis that clamp themselves to a tree trunk and look like a bump in the bark; and the vivid Mitchell's Daylight Roach Polyzosteria mitchelli, with transparent side windows, given here as one of the tourist attractions of the Mount Remarkable National Park.
Admittedly they warn you away from that one, owing to its habit of spraying you with poisonous oils if you interrupt its sun-bathing on top of bushes.
Then there's the gigantic Rhinoceros Roach Macropanesthia rhinoceros, aka Giant Burrowing Cockroach or Litterbug - a benign giant that grows to 80mm long, weighs 35 grams, and lives for well over 10 years. They spend the first 9 months of that in a permanent metre-deep burrow with its parents, and sharing the dried leaves they bring back. Roaches, as such a hugely successful group, have invented all sorts of reproductive behaviours - sticking their eggcases somewhere dark, carrying them around, and even live birth in the case of the Pacific Beetle Mimic. Macropanesthia eggs hatch before birth , and the parents take care to unusual levels, for a non-social insect.
They're also popular pets. Elsewhere in the world other species are available - Madagascan Hissing Roaches, for example. Slightly neurotoxic, those guys, so trying to eat 36 in a minute to get a season pass to a theme park was more than usually stupid.
And here, a range of other species kept by cockroach-fanciers - including Green Banana Roach, Domino Roach, and even interesting colour-morphs of the American Roach. Go look! Some of them really are vivid!
Aren't they pretty?