In the 1990s, the running community (the people who would later frequent letsrun.com, which had not been invented yet), thought most distance runners were clean. That was wrong.
Now, many on these message boards have swung the other way, suggesting that everyone is dirty. I wonder if that is wrong as well, if, ironically, the sport is cleaner now than 1970-2010. Think about it: there was no testing for a long time; and we know that people were blood doping and using roids; then there was the EPO era. Now there is more testing everywhere.
And I think there are a lot of reasons why most Ethiopians are clean. Back in the 1990s, people thought that European runners like Dieter Baumann were dirty but believed that the Ethiopians were clean. The view was the Ethiopians had all sorts of advantages, possibly genetic, but certainly advantages of dirt roads at altitude and group training and competition. The view was not that Ethiopians did not have access to drugs or had different ethical standards, it was just that they did not need to dope.
Why has that view changed? It just doesn't surprise me that Ethiopians are great runners. If they started beating Norwegians in cross-country skiing, then I would be suspicious.
Again, I'm sure that a bunch of Ethiopians and bunch of people from every country dope but not sure why people think that everyone is doping. And I'm all for increased testing everywhere as well.