The only way to handle the issue is when the players who are clean stand up to their union bosses and demand testing.
That runs along the lines of a conversation we had here on FreeRepublic a while back -- in which someone asked why pitchers didn't stand up and call for testing as a way to deal with over-sized hitters like Bonds, Giambi, etc. After giving it some thought, the general consensus was that this never happened because pitchers were probably using steroids as much as hitters were.