It's true that there are some notoriously bad (Asian) cheap restaurants... having said that, I've eaten out at cheap places around Melb CBD for years and never had issues with gastro.

Anyway, when you work for a restaurant kitchen or hear stories from friends, you quickly realise expensive places don't necessarily have optimal standards of cleanliness. Haha I guess the safest thing is to eat at home if hygiene is a big concern.