I once lost $100 to my colleague Craig Wolf when Mark McGwire failed to reach the Hall of Fame by his second year of eligibility. I was naive. I was foolish. I was wrong.
But I don't think I was wrong about McGwire's Hall-worthiness; I was wrong about baseball writers' ability to judge players without prejudice.
Sure, McGwire (and Bonds and Clemens and etc) used PED's. But so did a huge chunk of the guys they was competing against (just like Willie Mays, Mike Schmidt, and Whitey Ford before them).
We don't compare pitchers' ERAs in 2012 with those of the dead-ball era because stats fluctuate between eras. But dominance among peers remains the best indicator of Hall-of-Fame worthiness and during the "steroid era," when PEDs were largely legal. The playing fields were level.
Anyway, my opinion doesn't matter for much, so read Jonah Keri's more in-depth Hall argument for the most dominant "performance-enhancers" just recently eligible for induction.