What is it called when competition businesses purposefully attack or slander the competition?
The practice of showing the competitions product, likeness, or information inside your advertising is called comparative advertising.
There really isn't an ad term for slandering the competition beyond legal terms like slander and defamation. There are an abundance of laws on the books to keep this kind of thing from happening.
Not saying this doesn't happen but this is usually in small markets/towns. Some of the words around these ads are attacks and battles.
The term negative advertising is most often used for political ads, but is also used occasionally for non-political marketing that directly attacks a competitor.
The term more commonly used in an advertising context, as RyeBread suggests, is comparative advertising. This is a more neutral term and includes more neutral comparisons ("The same towels at a lower price") that might not be considered an "attack" or "slander."
Terms such as trade libel or defamation are legal terms. Not all comparative advertising, or even all negative advertising, is illegal, so these have a much narrower sense.
It is a subjective answer.
If I may clarify your question:
What is the term used by the news media or other advertising agencies to present their opinion that a competitive business advertisement either contains untrue or harmful statements (slander) or true yet strong criticism (attack) written in a hostile manner?
The answer: Depending upon how they want you to react - that's what they will call it.
I'll take some of the answers above and tell you what they really mean:
- "unfair trade practices": Don't invest in the company - insinuating the product must be inferior, when in truth the product is fine.
- "comparative advertising": This term would not be used for an attack or slanderous advertisement.
- "negative advertising": It is an unfair comparison between the products. Not "apples to apples". Different products will always have different strengths and weaknesses.
It can be called "Industrial Espionage"
You can find more on wikipedia: