From my observations, most Nigerians are making money by selling their Adsense account, because probably it isn't easy to get one.

Also from my research, big websites have zero to few Adsense ads on their site. Most sites rent out advertising space or are heavily into Affiliate Marketing.

For those buying the Adsense accounts, do you get paid P-P-C (Pay Per Click) or is there a more beneficial pay system offered by Google's Adsense

In essence, how profitable is Adsense?