One I've lately considered is how marketers so frequently use language, voice, examples, and reasoning that have nothing in common with the people they address.
A quick example from last year: A company wanted to address a specific business segment I knew. The clients said that the marketing people in these target companies didn't have a lot of influence on decisions while IT groups did. But at the same time they wanted language "sexed up" to appeal to ... the people who are used to creating and consuming marketing messages and who weren't so in the decision process.
As a colleague of mine quipped on the topic, "I'm too sexy for my ad, too sexy for my ad."
The very language that the decision makers use was proscribed by the company's marketing team because it wasn't what they liked to hear. Unfortunately, the people setting the language requirement also weren't the ones paying to use the products.
This isn't some new problem. I remember years ago reading an anecdote -- it may have been in David Ogilvy's Confessions of an Advertising Man -- about some then-young copywriter to people producing an ad about clothing. The creative director said that they would use an illustration rather than a photo. The copywriter asked why. "You always use illustrations in clothing ads," the expert said.
It was a habit on the part of the creative director. Even if illustrations would pull better, though, the answer avoided the question. The person didn't know why, and that's always bad because you can never learn if there's a better way.
Communication is a process between two people. They may be remote, as in a lot of marketing and media, or close. But however far removed, you need to speak to your audience in the language they use. Otherwise, it's akin to addressing an Athens audience in Lithuanian. Not much is going to get through.
(Speaking of Ogilvy, I just came across some quotes by him on various aspects of advertising. One was, "Use their language, the language they use every day, the language in which they think." As well as the admonishment, "A consumer is not a moron," so don't address him or her as such.)
Just as the ad director had a habit of using illustration for fashion, and presumably a long list of musts for how every little thing must be marketed, many marketers today have language habits.
Pay attention to ads that you see. How many split a single sentence into parts, as though a series of short sentences? It's a hackneyed trick, but many have adopted it as received wisdom. How often do ads targeting millennials try to use "hip" language?
You will find many other ticks, phrases, and remnants of marketing argot in almost any marketing you see. It helps explain why so much of it sounds identical. You could take examples from two competitors, redact the names, and you might not know which belonged to whom.
If you want to market and sell, then learn to understand your customer. Understand their concerns and motivations and consider how the product or service could address them. If you haven't spent time with people in the target audience, find someone who has and who can phrase things appropriately.
Most importantly, stop assuming that the way you've always done something, or the way the people who taught you did it, is automatically correct. Try different approaches and test them. I can guarantee you that you'll spend some quality time being astonished by things that actually work if you give them a chance. And by how much you assume that won't.