The advantage of this type of link is that it will let the visitor see the link and be able to use it to jump to your "Privacy Policy" page (or whatever unimportant page) without passing ANY of the page's PagaeRank "power" to your unimportant page because Google and the search engines can't "see" the link.
And why would you want to do that?
My advice is not to waste your time chasing your tail with these sorts of tricky techniques. Anything that sounds "clever" is probably, at best, a waste of time, and at worst spam.
Instead, focus on giving your users what they actually want. Do something productive like writing some additional content, providing them with a resource that they really want, or go out and get some good old fashioned PR. Public Relations that is.
The notion that the SE algorithm is something to be "cracked" and that Search Engines should be fooled is not the best approach to long term success. Instead think positively. What can I do to make my site the best? What can I add to make users keep coming back to my site, time and time again?
Your users are the most important ppl you have, so do what ever you can to make their experience better. Every time you attempt something, think: Is this making my site better for my users? If not, it is probably best not to do it.
Sure, make your sites search friendly, but going overboard with funnelling PageRank and the like is just time better spent elsewhere IMHO.