This definitely wouldn't be one of my "golden rules". Most HR departments/recruiters have a 6 second rule when it comes to looking at applicants; if you haven't caught their eye within the first six seconds, you're tossed in the trash. I certainly wouldn't be concerned about upsetting someone by perhaps wasting their time maybe with them thinking I'm not best suited to a particular role. Someone in a HR department isn't going to remember you either way from your CV so just go for it. I wouldn't advise someone who doesn't know the difference between a router and a firewall to apply for jobs that state "must be CCIE" but that would be more for their moral rather than it being a career limiting move. You can't expect a prospective employer to have confidence in your abilities if you don't have confidence yourself.