I came across this job posting: http://www.justin.tv/jobs/jobs. The page contains some bad language ("No bulls--t"). I personally find this vaguely offensive, and it would certainly put me off applying to work there: It made me wonder what kind/personality of people work at this company. At least where I'm from (EU), the language would be considered bad form, and it would be seen as badly representing the company.
Some job postings seem to go to the other extreme, filled with vacuous people skill descriptions and irrelevant details.
It's tempting to dream up pictures of each company based on their job posting.
So, does professionalism in job postings matter? Are you inclined to see through bad language, irrelevant corporate speak and so on, or do these affect interest in a job?