The Prophet (sal Allahu alaihi wa sallam) said: “Avoid swearing falsely in order to sell your goods. Apparently it appears to be promoting your business, but in fact it lets your business down and damages the goodwill of your business.” [Muslim]
The Prophet (sal Allahu alaihi wa sallam) taught us everything of use to us, including business ethics. He told us how false advertising - making incorrect claims about the product we want to sell - hurts the business. Even if it appears to be increasing sales, it is damaging in the long run.
Does this mean that if I am willing to take on long term loss for short term gain, I am free to do so? No, because false advertising is still lying and lying leads to the fire of Jahannum.