I was just reading this http://www.monetizers.com/fake-pr.php and thinking about how many people here waste money buying links on word clouds and blogs without checking the backlinks of the site at least. Do you check extensively every site you buy links from?
Depends on the price. Typically at least check yahoo and scan throught the links. But if I'm only paying a few $, I won't go to too much effort.
When you buy on forums, reputation and the itrader system do give a good idea about things. But as some of the others ahead of me have said in this thread, you aren't going around to check the authenticity if the link is worth a buck or so.
Basic rule of buying applies to all commodities , be it links, house, moped or your underwear. You just do not go to the market without first getting some info on the product and company so why would link buying be or should be any different?