The only bad rep usually comes from reptile keepers who do not take them out when their lizard is done.
For example, when i was eight i did not know much about my leopard gecko, and i never took the food out. The crickets took most of three fingers and nip of his tail.
Crickets can be vicious animals in the sense that they will nip at your animal, but you can not blame them since it is in their nature, rather, they should blame themselves for leaving them in the cage.
Also i used to raise crickets and they smell awful, well until i got springtails and those little black guys (worm like things) that sometimes come with crickets from pet stores. They cleaned up waste.