Its interesting reading this thread, some ppc works for some , but not for others and it can also be done not just to the traffic but how well your landing page or pages convert, the niche your working etc etc.
goclick like a lot of the 2nd and 3tier ppc engines also work the partner scheme of sharing traffic from different search engines for example goclick purchase a lot of their traffic from
http://www.ampkeywords.com/ which used to be a dedicated ebay supplier until they decide to offer its services to everyone.
I run my own dedicated Theme PPC search engines and can never please all of the people all of the time and when l have bothered to look at their websites and business have often found that they have constructed their promotions incorrectly, wrong keywords , page will not convert etc
At the end of the day these guys either rebook traffic or go with someone else, but someone always replaces them and thats the same principle the big guys work as well................
Just to end my little blurb when l have been asked to look at corporate brand name accounts and the budgets they spend on adwords, most of them could cut their bills greatly but the guys that they have placed their accounts with to place their ppc ads feed them shit and keep them in the dark , its called the mushroom method of adwords, because if they really picked the best keywords for the clients then they wouldnt be able to rip them off they way they do, in other words they just use financial muscle to pay for number one spot and anyone can do that....shit ppc leads or not nicho