Another candidate, with a different employer, told the person who was considering interviewing him (despite the errors in his cover letter) that his email was unprofessional and critical. This person would have gotten an interview because he had a connection. That connection was the reason that the employer suggested the candidate review his materials for typos before sending them out.
Don't Burn Your Bridges
I'm not sure when it has ever made sense to be rude or to burn bridges. Sometimes the person hired doesn't work out and the other candidates may get called back for another interview. No employer in his or her right mind is going to call back someone who said "your loss" to them. It won't happen.
Why do job seekers sometimes sabotage their chances? I suppose it could be the fact that it's easy to shoot off an email without reviewing what you wrote or because you're angry that you didn't get the job or the interview. Or perhaps some people don't know that all your job searching correspondence needs to be polite and professional. Even if you're angry or upset. It also needs to be typo-free and grammatically correct.
How Not to Get Hired
There are other ways to make sure you don't get hired. One person I'll always remember not hiring was the gentleman who starting taking off his shirt to show me the scar he received in an accident, in order to explain why he had been out of work. Another was a young lady who, after telling me her life story and then some, asked to use the phone to call a cab and asked for cab fare.
The Basic Rule of Job Searching
If there is one basic rule of job searching, it is to always act professionally. Communicate, dress and act with class, regardless of the job you are applying for. Believe me, the employer will notice and your chances of getting the job will increase ten-fold!