Halachos of Marketing

Telemarketing

1. A telemarketer who as a desperate gesture insults the consumer is in violation of onat devarim.
2. Calling at an inconvenient time such as dinner time (all the more so in the middle of the night) such that the consumer will interrupt his dinner to pick up the phone is a violation of onat devarim. Furthermore, the telemarketer who tries to convince consumers who aren't interested to buy the product are in violation of lo tachmod and lo titaveh of the consumer's money.
3. Negotiating for a discount isn't lo tachmod or lo titaveh since the seller is willing to sell it at the right price and setting a price isn't a final decision rejecting the offer. However, if the seller says he is convinced of the price and isn't willing to lower it, negotiating or convincing that resort to empathy or emotion or the like are a violation of lo tachmod.
4. Soliciting for a charitable cause even using persuasive tactics isn't a violation of lo tachmod or lo titaveh since you are helping them fulfill a mitzvah. However, persisting and pestering a potential donor are onat devarim.

False Advertising

Superlatives

1. One is not allowed to use superlatives to present a product if the superlative will likely deceive a reasonable person.
2. It is one's responsibility to gather relevant information on products one intends to buy.