I'm not sure there is an equivalent phrase, Al. Uncouth is not automatically regarded as unattractive in the USA, though it may be.

"Rough as a corn cob" is the phrase that also came to mind for me, as it did for BWL. While a phrase that can be used to be derogatory, it is usually more descriptive than judgemental. It might imply rough manners or outspokenness, or a lack of "couth," but often also conveys some quality of admiration, such as "speaking one's mind" even if without lack of finesse. While not a classless society by any means, my impression is our American society is less class conscious, and somewhat less likely to make negative judgements about a person's worth,or to guage them "unattractive" based on their social finesse or couthness than may be the case in the UK. "Roughness" may even been deemed something of a virtue.

Context, of course, is everything, and I don't have enough knowledge or experience to place your description in context.