Translated part of interview: Does doping ever become an option when your livelihood depends on it?
No. But the [global] anti-doping system is too bad. We Germans do quite well, but as long as there is no standardised global system, as long as a blood sample can't be transported out of Africa without being corrupted and as long as corruption is a dominant factor in these countries, you can pretty much forget the [global] fight against doping. There are countries where athletes lock themselves into military bases and don't let anti-doping officials in. Two years ago, in Iten, some doping officials appeared at one end of the track/town and on the other side pretty much entire squads just jumped fence.
German original:http://www.faz.net/aktuell/sport/800-meter-laeufer-schembera-der-sinn-des-laufens-ist-der-sieg-13717615-p2.html
He also is suspicious of other Europeans and Rudisha (for not being close to vomiting after his WR and seeming pretty unfazed).
In fact, pretty much anyone who runs faster than 1:45 (or atleast improves by 2 seconds from 1:45 to 1:43 in one year), the way it sounds like.