Hello,
Yashar koach for your desire to conduct commercial life as is proper. The kashrut of money is one of the most important foundations of the Torah of Israel.
These sensitive and important issues are not defined sharply in halacha. This is due to the fact that it is very difficult to determine when ordinary methods of commerce and advertising become pressure or coercion. Likewise, from the other side, it is difficult to determine when we are dealing with a customer who is making a free choice, who after hearing your words is persuaded, and when it is someone upon whom your pressure forced him to do what he does not want to do.
Not only this, but a significant part of modern commerce is the creation of need. For example: very often there is no real need to upgrade, and in general, it can be assumed that in every home there are numerous products purchased even though one could have managed very well without them, but suppliers created in various ways, a feeling of need and an impression that one cannot manage without them.
However, it would not be correct to say that everything is permitted. The Torah prohibition “Do not place a stumbling block before the blind” is interpreted by the Sages also as a prohibition against giving a person advice that is not in his best interest:
“…If he asks you for advice, do not give him advice that is not suitable for him. Do not say to him, ‘Go out early,’ so that bandits will attack him; ‘Go at noon,’ so that he will suffer from the heat. Do not say to him, ‘Sell your field and buy yourself a donkey,’ when your intention is to circle around and take it from him. Perhaps you will say: ‘I am giving him good advice’? But the matter is entrusted to the heart, as it is said: ‘And you shall fear your God; I am the Lord.’”
The conclusion of this Midrash gives you the straight compass by which to act: these matters are entrusted to the heart. If it is ordinary commercial practice, and the product is one that perhaps the customer does not strictly need but will nevertheless serve him well, it appears to be permitted. However, if you know that the product is entirely unnecessary, and your only interest is your personal gain, this is placing a stumbling block before the blind, and one who acts with integrity does not do this.
All the best,
Rabbi Yuval Cherlow
Rabbi Cherlow is the Head of the Ethics Department at the Tzohar Rabbinical Organization
