A key to good writing—I'm thinking especially of marketing writing and technical communication—is building trust between the writer and the reader. Trust flourishes when the reader has confidence in the knowledge and good will of the writer. Just a few mistakes in grammar and usage can make that confidence crumble—and with it the trust you've worked so hard to build.

In honor of Halloween, here are the top seven writing mistakes that make me cringe in horror:

7. Comprise and compose: The United Kingdom comprises England, Northern Ireland, Scotland, and Wales. Those four countries compose (or make up) the United Kingdom. Some would say that our language has evolved to where comprise means what compose used to mean, or that comprise now simply means both things. But can we really call it evolution when the distinction used to be clear and now it's fuzzy?
6. Lay, Lady, Lay: Sincerest apologies, Mr. Dylan. But I think you meant to say “Lie, lady, lie.” To some of us, the difference between lie and lay still matters.
5. Word mashups: Alot of the time, in fact just about everyday, I see copy with words mashed together. Alot isn't a word. And everyday, while a perfectly good adjective (it means commonplace), isn't a noun. Incidentally, I've just about conceded that the language has evolved to admit alright as a word. But I still don't like it.
4. Sloppy Latin abbreviations: Honestly, I can't think of a good reason to use Latin abbreviations in formal writing or even in marketing copy. But they're handy for casual communication like email. Remember, though, that i.e. and e.g. aren't interchangeable. They don't mean the same thing. And et is a whole word, so I don't want to see et al. with an extra period.
3. Archie Bunkerisms: You had me at hello. But you lost me at malice of forethought, heart-rendering, and (a particular favorite) for all intensive purposes.
2. Begging the question: “Beg the question” is a perfectly useful phrase, meaning that a debater (or anyone trying to make a case) has assumed the truth of the conclusion. But I almost never see it used that way. Instead, “that begs the question” has come to mean “that leads us to the question.” You might say that the language has evolved to embrace this new meaning, and so should I. But this is my list, so I'm keeping it here.
1. Degrees of uniqueness: Uniqueness either is or it isn't. Tell me that your product is the most unique thing on the market, and I'll roll my eyes in that unique way that I have. Other than nearly, almost, and maybe truly, I can't at the moment think of any other adjectives that play nice with unique. And I'll probably raise an eyebrow if you use truly.

You might protest that most readers don't know these rules, and most of the rest don't particularly care. But some of us do care. And many others notice, perhaps on a subconscious level, when the writing has flaws. Even a subconscious sense that something's not right can be enough to undermine your reader's confidence in you. Once you lose your reader's trust, you have a lot of work to win it back.