SEO Question for back links without anchor text

Question

What would be the benefit of having a back link with no anchor text? A friend of mine got a message asking if he would do a naked back link on his blog.

Answer 1

A "nacked" back link would not even be displayed. Therefore the point is to "show" it to the search engines and hide it from real users. This probably falls into the domain of "black hat SEO" and may be penalized if discovered by the search engines.