This topic has been covered extensively on this posts
1) The sporting prowess of Kenya was noted 50 years ago when this country was still fighting for black civil rights (link provided below)and Kenya was newly independent (see link below)
2) Kenya is very poor country it does not have the resources /pharmaceutical base to sustain BALCO like affairs.
3)Kenyans are tested like anyone else when they compete this has been discussed ad naseum
4)The percentage of top Kenyans that have been implicated in PED is neglible. Kenya and Ethiopia have never lost a medal due to drugs, very few other top nations boast of such records
5)Finally, as a social creature, do you think that the world would allow some scrawny Africans to win unfairly? There are a lot of people like you all over the world with biased views about certain people and if there was even a hint of systematic doping in Kenya, all their athletes will be painted with one bad brush
6)EPO is a drug that is used in treating conditions ranging from kidney failure to cancer, the fact that you can buy it in a chemist in Kenya is due to the fact that in Kenya you can buy any drug, I have been to Kenya and any Kenyan on this board will concur that pharmaceutical controls are lax. When I say you can buy any drug at the chemist, I mean anything ;)
7) Sit back and enjoy human endeavor which ever country it might be from, some people will be better than you in somethings.
http://sportsillustrated.cnn.com/vault/article/magazine/MAG1079410/index.htm