Steroid-using athletes avoid detection successfully

Recently Alan Abramson published an article where he noted whether tests conducted by the World Anti-Doping Agency (WADA) were effective.
The WADA conducts many tests for steroids and other performance-enhancing drugs each year. It seems that those that apply steroids and/or other related drugs are caught. You may believe that the world of sports and bodybuilding will be soon cleansed from application of forbidden medicines. For example, numerous tests for banned medications have been conducted at the 2012 London Olympics.
But several questions appear here. Are these tests sophisticated enough to detect any athlete that dopes? Are these tests effective?
Let examine results of several tests. In 2010 the WADA publicized statistics according which 258,267 samples were analyzed by 35 WADA-accredited labs. Out of these samples 4,820 results were atypical findings. About 60 % of positives indicated about intake of steroids. Many positives were for cannibinoids. 10 % positives were for marijuana. As you see, only 60% out of those who took forbidden drugs applied steroids. Is it real? Don’t display the results of the tests that the WADA doesn’t do the job properly?
The former president of the WADA Dick Pound believes that at least 10 % of sportspersons who took part in the 2012 Summer Olympics applied steroids. He affirms that those steroid users that are not clever are caught by anti-doping agencies. He also affirms that a sportsperson that has been caught doping will fail an IQ test. He concludes that just unwise sportspeople don’t avoid detection.
Thus, when you read that the WADA has conducted many tests to make sports clean, think whether these statements are true. Is able the WADA to make competitions fair? Why does the WADA notice about number of tests?
It seems that the WADA just wants to convince people that the job is done properly. The WADA tries to secure future funds. It is the reality.