I just read an interesting story on Fanhouse posing the question if the NBA has a steroid problem, which I recommend you read.
A lot of the discussion centres around speculation on Golden State Warrior Stephen Jackson's 8th NBA season which is shaping up to be the best of his career. Jax is posting career highs in scoring (21.2), assists (6.6), rebounds (5.0) and most importantly minutes, clocking in at 40 a game, leading the league. Now no one has any knowledge or info that he has been taking any performance enhancing substances, the speculation comes from him performing at such a high level later in his career.
While I'm not here to put Stephen Jackson on the stand, I'm saying that it is entirely possible that players would do whatever is necessary to gain that competitive edge. With only so many spots available in the NBA and the "perception" that steroid usage is not a basketball thing, the league may want to stop worrying so much about what people are smoking, and start determining if people are injecting.