Randomised controlled trials (RCTs) are considered the ‘gold standard’ by which novel psychotropic medications and psychological interventions are evaluated and consequently adopted into widespread clinical practice. However, there are some limitations to using RCTs as the basis for developing treatment guidelines. While RCTs allow researchers to determine whether a given medication or intervention is effective in a specific patient sample, for practicing clinicians it is more important to know whether it will work for their particular patient in their particular setting. This information cannot be garnered from an RCT. These inherent limitations are exacerbated by biases in design, recruitment, sample populations and data analysis that are inevitable in real-world studies. While trial registration and CONSORT have been implemented to correct and improve these issues, it is worrying that many trials fail to achieve such standards and yet their findings are used to inform clinical decision making. This perspective piece questions the assumptions of RCTs and highlights the widespread distortion of findings that currently undermine the credibility of this powerful design. It is recommended that the clinical guidelines include advice as to what should be considered good and relevant evidence and that external bodies continue to monitor RCTs to ensure that the outcomes published indeed reflect reality.