Obviously I need a reality check.
I agree with you that some runners could be doping. The rise of the Spaniards in the marathon in the mid-late 90's certainly raised eyebrows. I just get annoyed that a lot of people on this site refuse to believe that great LEGITIMATE performances are possible. Yes, there are cheats, but lets take a simple example.
Ron Clarke ran 27:39 for 10,000m in the 60's. I think it is very feasible that athletes who have many natural advantages (Paul Tergat, Haile Gebrselassie, etc), combined with natural time progresions could be running over a minute faster thirty plus years on. Why is that hard to believe? Thirty years before Clarke, athletes were running about two minutes slower then him.
The key factor which I believe supports my argument best is that no (or very few) non Africans are getting caught for EPO either. Some people say that Americans for example will not dope because they are tested more often and so will not risk getting caught. This is a stupid argument (not your argument but I have read such things on other threads). Look at cycling. Are the top cyclists not doping because they are worried of getting caught? No. Cycling (grand tours) is completely different to distance running.