Any athlete should be slapped hard on general principles for taking recreational drugs. Their penalty should be shame and ridicule.
To be fair to the clean ahtletes, the recreational-drug-using athletes should be officially penalized in some way. The penalty wouldn't be so much for the possible performance-enhancing attributes of the drugs as the negative image such use brings to the athletic world.
An athlete who uses recreational drugs gives the impression of being a bit of a low-life, one whose integrity is questionable. In today's drug-enhanced athletic environment, anyone who takes recreational drugs could easily be seen as susceptible to also taking performance-enhancing drugs, and they would automatically bring suspicion upon themselves, even if the suspicion is, in reality, unwarranted.
Today's athletes and their respective governing bodies should do everything they can to avoid even the mere suspicion of illegal/recreational drug use, blood doping, etc. Athletes are role models, and they should understand and respect this; illegal/recreational drug use sends the wrong message to impressionable fans.
Athletes deserve respect for their dedication to their sports, but they should earn their respect cleanly.
Scott