If marketing is a profession, and I hope it is, then I suggest there are five rules that marketers should not follow in the interests of self-respect and respect for the profession.

It pays to pander.

No it doesn’t. It’s unethical, but also unwise, to exploit the uglier impulses and less-than-noble dreams of consumers, because a brand that’s built on such appeals will find it hard to grow to be a source of pride. Apparently misogyny, xenophobia, and contempt for the disabled have worked as customer acquisition tools for soon-to-be President Trump. But will they be retention tools? Consumers who’ve succumbed to the lure of guilty pleasures, to the point of being coy about acknowledging them to pollsters, will face bigger coming-out problems down the road.

Sell dreams even if you have no plan to deliver.

If you’ve been promising jobs in demolished steel mills or shuttered coal mines, better health insurance with lower taxes, remember the essence of a brand is promise, large promise. Pin your brand to a dream, yes, but have a plan or today’s happy buyers will become tomorrow’s angry owners.

Win at any price.

Your offering lives in an ecosystem. Don’t poison it. The more vivid the negative advertising, the longer it lingers. Brands depend on the health of the whole system through which value is created and sustained. If you compare your brand to “Crooked Hillary,” “Lyin’ Ted,” “Low Energy Jeb,” and “Little Marco,” the price of winning may be contempt for the whole category.

For more on Donald Trump, watch this video:

Scorn the non-buyer.

Trump alienated the marginal customer. He forgets that today’s brand rejecter may be tomorrow’s opportunity, but not if the marketing campaign has cruelly cut the market into segments of mutual hatred.

Lie.

Every professional traffics at least a little in hopefulness if they want to be hired. In marketing, hope takes the form of indulging puffery and exaggeration. The problem is that the temptation to shade from puffery to lying is always present. And the suspicion lurks that big lies are safer than small lies. Adolf Hitler articulated this hunch when he said, “In the big lie there is always a certain force of credibility: (people) more readily fall victims to the big lie than the small lie, since they themselves often tell small lies in little matters but would be ashamed to resort to large-scale falsehoods.” How Trump the marketer ranks on size of the lie is a matter of opinion, but someone who hoped to learn ethical practice from his marketing manual would be well advised not to follow him in the matter of frequency. The Washington Post scored 64 percent of the statements of his as 4 on its 4 point severity scale, and most of the rest at 3. Its summary was, “There’s never been a presidential candidate like Donald Trump—someone so cavalier about the facts and so unwilling to ever admit error, even in the face of overwhelming evidence.”

This then is the danger of treating last week’s election as a lesson in marketing. Pandering, blustering, insulting, alienating, and smothering facts with falsehoods does seem to work. In the short term. But at the risk of poisoning the market.

John Deighton is Baker Foundation Professor of Business Administration at Harvard Business School.

This article originally appeared on Harvard Business School Working Knowledge.