The Gemara on Amud Aleph speaks of a substance known as kala ilan, a dye that could be used as counterfeit techeles, which could have serious consequences. If the user thought he was fulfilling the mitzvah of tzitzis, he would allow himself to affix wool tzitzis to a linen garment, which overrides the prohibition of shaatnez. But if the techeles is ersatz, sold to him by a fraudster, then he is not fulfilling the mitzvah and is de facto violating shaatnez.

There is an allegorical significance to the idea that something can so closely resemble a mitzvah and piety and yet actually be sinful. Rav Moshe Amiel (Le-Nevuchei Hatekufa 4:12) observed that Jews tend to be at the forefront of every revolution. They are the strongest advocates for socialism, woke-ism, atheism, or any “ism.” In truth, he says, it all stems from a deep drive for justice, even if misguided and distorted. However, even the distortion has meaning. After all, why did God design a world not only with techeles, but also with a close, yet fake analogue? In a strange way, though the lesson may indeed be that kala ilan is invalid, it looks like techeles, and perhaps even the person thinks it is techeles. That is dangerous, but nonetheless profound—a mixture of good intentions, fraudulent peddlers, and misguided beliefs.