There are weight scales that additionally claim to measure body fat by electrical resistance. According to this article, body-fat scales are "absolutely" superior to just-weight scales, although the article ads the reasonable caveat that one should simply expect consistency, not a number that's precisely what one would get from an immersion test.
On the other hand, the article then goes on to list so many steps to get consistent results (clean the pads with alcohol) that I wonder if it's just making excuses for a technique that just has too many variables for a consumer to control.
Is there good evidence that consumer-grade body-fat scales can produce consistent results that highly correlate with body-fat percentage?