Parasitehosts Worth with and without related content?

Hello,

Im wondering if someone can say a word about the worth of parasite hosts. For example normally sites are taken where you place an article with a link. But these pages normally contain 10 to 30 links on these pages whil the own article only contains 1 or some more...

So how important is it to have an article on such page for the relevancy?

I mean there a forums out there that have pr9 on the maindomain which means they are probaly trusted by google and a profilepage only contains a small amount of links... So is it really so much better to have an article on the parasite host? Or is the effect of this going down because of the big number of links on these pages?

By the way... how much linkjuice is lost when using parasite hosts compared to direct backlinking? Or is there a gain by using these? If there is a gain wouldnt a chain of 50 web2.0 only linking to the next web2.0 until it links to the moneysite bring in big linkjuice? Or would it be better to link these 50 directly to the moneysite?

Thanks!