i remember a search engine called 7, when i first started. not sure if its still around, but you could actually pay money to get listed. it was like a bid engine, the more you bid the higher you'd appear in the serps.
google is starting to become a little bit like that.
if you take any of cien's examples above, then googles 'shopping results' appear above the genuine shops. but you can't honestly say that the shops in those results deserve to be above the likes of amazon. they are only there because they have jumped through google's hoops.
they might not have to pay any money like you did with '7', but you can still get listed high without being deserving it. not a lot of difference.