In spring training, 2004, Jason Giambi came back to the Yankees having lost 20 pounds and in "the best shape of his life." Always assume everyone is on steroids. I think Lebron James uses. I think all of his competition uses, too. I can't for a second imagine a reality where Kobe Bryant doesn't. Some do so conservatively, some do so aggressively, some do so with dangerous, experimental abandon. Lebron is the best- probably the best user among all of the users- still the best.
I think you do common sense a disservice when you call it a conspiracy theory. Professional athletes use drugs. We've learned that by now.
Common sense does itself enough disservice, it doesn't need us.
If we're 'always assuming everyone is on steroids' , as in all 450-ish guys in the NBA are on steroids -- which I suppose is possible, if unlikely -- then there's no problem, since the level of competition is roughly equal, insofar as everyone has access, incentive, and (apparently) no real risk at repercussions. No reason to make noise about it, then.
Going by your line of thinking the only reason steroids are a problem would be because you
don't think everyone in the NBA is using, because its an unfair competitive advantage that one player is getting and another one isn't.
Which leads to the same kind of tunnel vision about figuring out which ones are and which ones aren't that we see in this thread. Common sense is really a wonderful thing.