I received a resume with a cover letter that started out with a statistic on the labor market. Quoting statistics to make a point isn't a good lead in for a cover letter. Here's how the cover letter started:
Labor statistics indicate that people change careers an average of three times during their working life. At this time, I am looking for a new and long lasting career. Please consider my professional strengths as they apply to your current searches:
The remainder of the cover letter is pretty good and continues with several bullets detailing specific skills and accomplishments. Unfortunately, the first paragraph sets the wrong tone for the cover letter and resume.
My first impression was that the job seeker is making an excuse for changing careers. It shows a lack of confidence in their career progression and that they are trying to justify the changes they have made themselves. This impression was wrong. The actual progression of the job seeker was good, having worked in a single industry throughout their career.
The second impression that I had was to question the statistic. I've read that individuals will average five career changes. Is the stat I remembered right, or is the stat the job seeker quoted right? I don't know, and it really isn't important. The problem is that I was focused on thinking about the statistic, and not the content of the cover letter. This may have distracted me from the content for a few second. I realized that I had kept moving my eyes as if I was reading, but wasn't processing what I was seeing. I then had the choice to reread what I glossed over or skip it and keep going.
Bottom Line: Focus your cover letter on topics that help sell your potential to an employer. Content that doesn't promote you should be avoided. Unusual or unrelated content should be avoided as it draws the reader's attention away from cover letter and resume.