Originally Posted by Peter (IMC)

You´re confusing 2 different things. The spider trap (loop) you´re talking about happens in dynamic websites where the URL of the same page is different depending on the path you took to reach a page. It is better to change the programming of a dynamic website so that this doesn't happen. Using nofollows to prevent this problem isn't a good solution and might not even work that good.

If the URL's don't change, loops in the site because of links are no worry because the spider already knows it visited a page before.

You shouldn't care which pages a search engine shows in a backlink search. It's more important to have your pages show up when people search for your keywords, isn't it..