All the examples for Axis attempts at espionage seem to have ended badly or even leaving them worse off because of turned agents; the Allies seemed to have much less problems in that regard, considering operations like Minemeat. Why was this?
PART of it was that the man in charge of the Abwehr, Wilhelm Canaris, was, shall we say, imperfectly devoted to Hitler.
It's more complicated than that, though, and I too look forward to an in-depth answer.