Dont have any person experience with counterfeit testosterone preparations, but this is what can be found in the scientific literature
A good review that gets you started:
[http://www.tihcij.com/Articles/Conflicting-Information-and-Unknown-Risks-Surrounding-Counterfeit-Anabolic-Steroids.aspx?id=0000411]
Musshoff, Daldrup, and Ritsch (1997) analyzed forty-two anabolic steroid products found on the illegal market in Germany. In many cases, cheaper steroidal agents were substituted for labeled drugs. In 2000, Ritsch and Musshoff analyzed German black market steroids. As was similar to the previously mentioned inquiry, they found that fifteen of the forty samples (37.5%) contained a different compound than listed or no pharmacologic agents.
Coopman and Cordonnier analyzed 74 black market pharmaceutical preparations commonly distributed among bodybuilders. Twenty-five of the 74 products did not match their label. Of the 40 oil-based injectable steroids analyzed, the active ingredients in 21 (52.5%) did not match the label, one did not contain an active ingredient, and remaining 20 samples contained other or more active ingredients. In 2012, Pellegrini and colleagues performed toxicological analysis on 15 steroid preparations from the black market. Two of the samples were compliant with their labeling. In the remaining 13 preparations, there was either no active substance or the substance was different from the labeling.
In 2008, Thevis and colleagues analyzed seventy different drugs (steroids) confiscated from house searches. Forty-eight of the seventy samples were steroidal compounds. Seventeen of the 48 samples (35.4%) did not contain the declared ingredients. In most cases the actual content of the drug was a different type of steroid or steroid-blend than the label claimed.
Thirty-five percent (35%) of the products were significantly overdosed. Drugs that exceeded the labeled dosage did so by a range of 102% to 459% as compared to the label. Unidentified steroidal compounds were discovered in approximately 60% of the samples. Most of the unidentified compounds were found to be inert steroid precursors or other intermediary compounds.
Ita appears from the literature that ‘Faked’ Sustanone is frequently only composed of simple esters such as T enanthate.
Where I do have personal and professional experience is in the analysis of counterfeit biologics such as hGH or epo. I am in pharma working in analytics. We frequently get samples that were confiscated for analysis. Basically it confirms the findings described above. Frequently the dose is incorrect, impurities are higher (for example host cells proteins that come from the bacteria used to ‘manufacture’ the drug) and sometimes the identity is wrong.