Americans tend to be pretty savvy about advertising. Put a box around claims, annotate them with the words “paid advertisement” or “sponsored content” and most people approach those claims warily. Unfortunately, the same people who are dubious about advertising claims are remarkably gullible when it comes to quackery.

That’s the bad news. The good news is that it is surprisingly easy to tell quackery apart from real medical information. Quack claims are typically decorated with red flags … if you know what to look for. What follows is a list of some of those red flags.

1. The secret knowledge flag: When someone implies they are sharing secret medical knowledge with you, run in the opposite direction. There is no such thing as secret medical knowledge. In an age where there are literally thousands of competing medical journals, tremendous pressure on researchers to publish papers, and instantaneous dissemination of results on the Internet, nothing about medicine could possibly be secret.

2. The giant conspiracy flag: In the entire history of modern medicine, there has NEVER been a conspiracy to hide lifesaving information among professionals. Sure, an individual company may hide information in order to get a jump on competitors, or to deny harmful effects of their products, but there can never be a large conspiracy because every aspect of the healthcare industry is filled with competitors. Vast conspiracies, encompassing doctors, scientists and public health officials exist only in the minds of quacks.

3. The flattery flag: Quacks invariably try to flatter potential customers by implying that those customers are uncommonly smart, insightful and wary. They portray non-believers as “sheeple” who are content to accept authority figures rather than think for themselves. A real medical professional does not need to flatter you. He or she knows what is true and what isn’t and shares that information whether it makes you happy or is the last thing you want to hear. You can believe it or not.

4. The toxin flag: I’ve written before that toxins are the new evil humors. Toxins serve the same explanatory purpose as evil humours did in the Middle Ages. They are invisible, but all around us. They constantly threaten people, often people who unaware of their very existence. They are no longer viewed as evil in themselves, but it is axiomatic that they have be released into our environment by “evil” corporations. There’s just one problem. “Toxins” are a figment of the imagination, in the exact same way that evil humours and miasmas were figments of the imagination.

5. The “brilliant heretic” flag: The quack often has no training in the relevant discipline, be it obstetrics, immunology or cancer care? No problem. A pervasive theme in quackery is the notion of the brilliant heretic. Believers argue that science is transformed by brilliant heretics whose fabulous theories are initially rejected, but ultimately accepted as the new orthodoxy. The conceit rests on the notion that revolutionary scientific ideas are dreamed up by mavericks, but nothing could be further from the truth. Revolutionary scientific ideas are not dreamed up; they are the inevitable result of massive data collection. Galileo did not dream up the idea of a sun-centered solar system. He collected data with his new telescope, data never before available, and the sun-centered solar system was the only theory consistent with the data he had collected.

6. The “quantum” flag: Quacks love to baffle followers with bullshit, hence the invocation of esoteric scientific theories that they don’t understand. Quantum mechanics and chaos theory are two incredibly abstruse scientific disciplines, heavy on advanced math. If you don’t have a degree in either one, you aren’t qualified to pontificate on them. The same thing applies to new, imperfectly understood areas of science like epigenetics or the microbiome. Both are genuine scientific concepts, but we are in the earliest stages of elucidating them. There is real danger in insisting that they have current practical implications. We should learn from the terrible mistakes that were made when radiation was first discovered and and radioactive compounds were added to everything from water to make up under the false belief that radiation could prevent everything from aging to death.

There is a saying in science that “extraordinary claims require extraordinary evidence.” Quack claims are typically extraordinary, but quacks don’t offer evidence, they raise some or all of the six red flags in an attempt to trick you into buying what they are selling, and they are invariably selling something. When you see one of these red flags, you can be virtually certain that you are in the presence of quackery. Run, don’t walk, in the opposite direction.