Spiders and mantis are not dirty. In terms of living habits, spiders and mantis are relatively clean insects, and they usually keep their nests or habitats clean. Spiders' nests will become dirtier and dirtier over time, but they will rebuild their nests when necessary and keep them clean and hygienic. Mantis will also keep its habitat clean to avoid attracting natural enemies and diseases. So generally speaking, spiders and mantis are relatively clean insects, and no one is dirtier.