Never write an advertisement which you wouldn't want your family to read. You wouldn't tell lies to your own wife. Don't tell them to mine.
If you tell lies about a product, you will be found out - either by the Government, which will prosecute you, or by the consumer, who will punish you by not buying your product a second time.
Experience has taught me that advertisers get the best results when they pay their agency a flat fee. It is unrealistic to expect your agency to be impartial when its vested interest lies wholly in the direction of increasing your commissionable advertising.
Never write an advertisement which you wouldn't want your own family to read. You wouldn't tell lies to your own wife. Don't tell them to mine. Do as you would be done by.