Ah, now, y'see Indurain I found it harder to believe than with the others. Partly because of his style of riding - he flattened his opponents, I mean trounced them over 3 weeks, not so obviously explosive as we're led to believe PEDs do. But also partly because he was so quiet, unassuming etc
But then I ask myself well his main adversaries were all on the juice so he MUST have been. His reaction to Riis' "confession" smacked of guilt too although I can't recall exactly what it was, just that I was suspicious at the time.
Got to remember too though that everyone reacts differently to EPO. Some respond better than others, so it's not necessarily fair to say "look at how Zabel's performance improved, ergo whoever beat him must have been on it".
For me it's more about the organisation of it, the culture of it, the Festina affair, the fact that from top to bottom riders were and are still now being caught.