Bad
promiscuous - Lacking discretion or selectivity, especially in choosing relationships or associates; mixing or combining things randomly.

The character in the novel was portrayed as promiscuous, frequently engaging in relationships without commitment or emotional attachment.
reprehensible - Describing behavior, actions, or conduct that is morally wrong and worthy of disapproval or condemnation.

Though he told people not to repeat it, it was reprehensible for him to spread rumors about his colleague, knowing it would damage her reputation.