Tejada wouldn't shock me. He went from average Shortstop on Oakland to MVP. I think it's pretty apparent that Sosa was on steroids, otherwise we'd all be celebrating him having the HR record clean. Don't get me started on Big Bad Brady and his historic sideburns. (somebody's gotta know what I mean)
It really doesn't matter if you trust him or not, Giambi isn't on steroids because he got hot and then cooled off a bit. I guess Todd Helton was on steroids because he's not playing well. Chris Carpenter hasn't pitched like this before, he's on steroids. Brian Roberts must be on steroids too, look at his numbers. Juan Pierre is having a bad season, he's probably off the juice.
You can accuse all over the place, but if you have nothing to back it up other than "well you know he's playing good and he wasn't before" or anything like that, you're going to look really stupid.
By the way, try to get a tumor and not play baseball for a year, and come back at the level you were at when you won MVP. It takes time to get everything going again, they're not machines.