Clickbait refers to deceptive links on internet pages, designed to trick someone into clicking on something that they would not otherwise click on, by tricking the person into thinking they will get something other than what is actually linked to. While some people try to trick users into coming to their page for various personal reasons, such as vanity, the vast majority of clickbait directs the user to advertising. The temptation to set up clickbait is not surprising, since it usually costs money to create internet content, and, without advertising, that money can't be directly recouped without creating complex "paywalls". That is, internet data is essentially free, just as television signals sent through the air are free, so advertising is used. As news distribution transitions away from print-on-paper (where the newspaper vendor can charge money at the time the newspaper is purchased) toward the internet, advertising becomes extremely important. Large news organizations (CNN, NBC, Fox, Huffpost, etc.) have to spend a lot of money on their reporting and editorial staff.
The temptation to hide a link to an advertisement behind what looks like a link to a real story is very real. A headline about a hurricane, linking to an advertisement about a resume-writing service, would be an example of clickbait, and would obviously be unethical. There are generally accepted standard of ethics here. News websites often have clear sections on their pages for "sponsored content", which means advertising, or, perhaps more properly, "infomercials". But mixing in advertising among the actual news stories is so important for raising revenue that news sites often have to include them, with a short disclaimer such as "sponsored content" or "paid partner content". Users know what to expect when they see that. The sponsored content is generally written in such a way as to be interesting to the reader—a lot of effort goes into making advertisements entertaining. News sites generally know how to behave in an ethical manner with their advertising.
A more general type of journalistic dishonesty is the practice of writing a headline or short article that says or implies one thing, with a link to some article or web page that actually says the opposite. This practice is extremely widespread and is perhaps the most common form of dishonesty. This is not properly called "bait" because the author presumably does not actually want the reader to go to the referenced site and read it. He just wants the reader to believe that the site says what the author implies, perhaps swayed by the authoritative nature (NASA, etc.) of the referenced site. It is common for articles to have "sidebar" types of links with an implication of "If you are interested in background, or more detail, on this part of the story, this site might be a good place to look." Misuse of that is dishonest.
- "Woman out of appeals after trial court says her firing for breastfeeding not sexist since men can lactate"—as Snopes points out, the headline is a gross distortion of the facts of the case