Verminous, meaning infested or teeming with vermin, can be negated by using antonyms such as clean, spotless, sterile, unpolluted, or sanitary. These words indicate the complete absence of any infestation, making the environment or object free from germs and pests. Additionally, you may use hygienic, healthy, or wholesome to describe a setting or area that is free from any type of filth or pollution. Alternatively, hygienic can also be used to indicate something that helps maintain clean and healthy conditions. Thus, using antonyms for the word 'more verminous' conveys positivity, cleanliness and pureness.