The information provided below is for public discussion and popular science purposes only and does not constitute any advice on experimentation, use or identification of illegal substances. Drug abuse and its identification and detection are extremely risky and illegal in many areas. If you encounter related problems, it is recommended to seek help from professional institutions (such as regular forensic or analytical chemistry laboratories) and never rely on subjective sensory judgment. There are some general views on the preliminary judgment of whether a substance is adulterated by color and smell, but it should be noted that these methods are neither comprehensive nor reliable: 1. Color observation • In theory, different chemical components or adulterants may change the color of a substance. For example, sometimes a drug with higher purity may have a uniform color, but after being mixed with other substances, the color may be uneven or have an abnormal hue. • In reality, however, color is affected by many factors (such as raw materials, preparation process, storage conditions and even differences between different batches), and adulterants may also be similar in color to the original substance, so it is often difficult to accurately judge whether it is adulterated based on color alone. 2. Odor detection • Some illegal drugs will leave a specific odor during the production process. Pure products may have a certain characteristic odor, but after being mixed with certain organic solvents or other chemicals, the odor may change. • However, smell is greatly affected by the subjective influence of the environment and individual feelings, and many adulterants may be odorless or have a well-masked smell, so it is also impossible to make a reliable judgment based on smell alone. In general, using color or smell to determine whether a substance has been adulterated can only be regarded as a rough and preliminary means of observation, and cannot replace professional chemical analysis techniques (such as chromatography, mass spectrometry, infrared spectroscopy, etc.). In addition, the characteristics of different illegal substances, different manufacturers, and even different batches of products vary greatly, and relying solely on external sensory characteristics can easily lead to misjudgment and dangerous risks. Once again, any issue involving drug identification involves legal and health risks. For those who are concerned about safety and purity issues, they should rely on reliable laboratory test results through legal channels, rather than relying on non-professional "sensory" judgments. At the same time, the safest practice is always to avoid contact with or use illegal substances.