Do your grammar and punctuation affect your credibility?

I believe that bad grammar and punctuation sabotage the credibility of the writer.  The same goes for the company that the writer represents.

For me, bad grammar and punctuation suggest a lack of education and attention to detail. I wonder if the writer’s professional work displays similar weaknesses. Plus, I’m annoyed if poor writing makes me work harder to grasp the point the writer was trying to convey.

Marketing materials–especially long-lived forms such as websites and brochures–should hit high standards to put the firm’s best foot forward.

I’m more forgiving of typos in quickly created, ephemeral communications, such as tweets on Twitter. I’m guilty of typos there and on my blog.

What about you? Does bad grammar and punctuation detract from your opinion of writers and their companies? 
Please answer the poll in the right-hand column of my blog. Also, feel free to leave your comment below.

I’ll report on the poll results in a future issue of my newsletter. The poll will run until June 2009.


Jan. 20, 2013 note: I updated the title of this post after an anonymous commenter pointed out my grammatical mistake.