Profitable Link Farms...??

The internet is full of sites that offer this or offer that. Well for some sites instead of having several hundreds of pages full of revenue generating links people have created sites with a few pages dedicated to one thing displaying a banner or keyword towards a topic of interest. However I have to think to myself if a site contains several hundred links on one page which aren't in directories or categories wouldn't that be considered a "Link Farm". Here are some site that in my opinion would be considered profitable link farms:

Milliondollarhomepage.com
500words.com
Onethousandpaintings.com (similar)

Well when it comes to the function of theses sites people purchase something from them and in return they get to place a static banner or link on the site for as long as the domain is purchased. I think it's a brilliant idea but how long will it last? Granted people find the hype to be a "heat of the moment" purchase but is the traffic to the sites that purchased a banner or link getting banned from search engines because they link to the profitable link farm sites..? And is the traffic that is purchased from the profitable link farm sites is it really relevant? Theses are questions I would ask myself before considering a link farm purchase.