Use 'pestilential' to describe what could cause outbreaks or spread disease.

Disease Connection

'Pestilential' often suggests negative, unhealthy living conditions or environments.

Negative Connotation

'Pestilential' implies a level of annoyance that is overwhelming or constant.

Irritation Level

Use 'pestilential' for someone whose behavior is suffocating or inescapable.

Overbearing Presence

'Pestilential' indicates something not just bad, but corrupting or degrading morals.

Moral Harm

The word carries weight and suggests extreme moral corruption or malevolence.

Intense Evilness

When describing moral harm, understand 'pestilential' is old-fashioned and less common today.

Archaic Usage

 from Jefferson on. "Cities are pestilential to the health, to the liberties, to the morals of man. If we continue to pile upon ourselves in cities, as they do in Europe, we shall become as corrupt as they are in Europe and take to eating one another as they do there." He apparently had a sense of humor.