Bad reputation related to Scamming... Take Romania as an example. They were first banned by eBay because they sold Planes, Houses and so on... which they didn't own, and since the government refused to collaborate in order to find these thieves, eBay banned the whole country from using eBay... Clickbank followed so did many others.
It has to do with the laws of the country. A lot of countries don't recognize private property or have any business rights. Clickbank could goto a country and be ripped off because the country will favor scammers. As well, regulations play a roll. Governments have a lot of red tape for businesses to go through, and if they have to hire a force of people to deal with red tape, for some small country that will only have a few people, isn't worth the time.