butt-ugly vs unattractive

butt-ugly

adj

  • Extremely ugly. 

unattractive

adj

  • Not handsome or beautiful or appealing. 

  • Lacking the power to attract interest. 

noun

  • An aesthetically unattractive person 

How often have the words butt-ugly and unattractive occurred in a corpus of books? (source: Google Ngram Viewer )