Antonyms for the word "well-thought-of" would be words that indicate a negative or neutral impression of a person or thing. Some possible antonyms include "disreputable," "unpopular," "unfavorable," "unrespected," "unknown," or "obscure." A person or thing that is disreputable may have a bad reputation or be considered unworthy of respect. Something that is unpopular may lack the approval of the majority, while something that is unfavorable may hinder or harm. An unknown person or thing may lack recognition or be ignored, while something that is obscure may be difficult to understand or find. These antonyms highlight the importance of a good reputation and how it influences the way we perceive others or things.