The main problem with certs can be demonstrating by googling the cert title or number + "dumps". You will find the exact questions and answers for most tests. (More on "most" in a moment.) I don't mean a detailed outline - I mean the full text of the question, the possible answers, and which one is correct. Memorize the answers and you pass the cert.
As someone who periodically participates in hiring, I don't see much value in certs. I've had the experience of people who had certs who didn't know their stuff. I've never known any employer who given a choice between someone with many years of experience and someone with a cert, would choose the latter.
There are other problems with certs. I've always found the format is quite ridiculous. Why should I memorize things? If they test concepts, that'd be one thing, but often certs are "which of these commands is correct" kind of questions. What, am I trapped on a desert island with a datacenter to administer and no manuals?
That said, certs can't hurt. I find them valuable to study for though less to actually take. Vendors outline everything to get a basic knowledge, and that's useful to go over. The only time I see real value in certs is
- Your employer is a government agency or some kind of big bureaucracy and they require the cert for a position.
- Some vendors will only extend certain partnerships ("Gold VAR" or whatever) to companies that have X number of certified technicians
- Your company is providing services and wants to be able to say "all our techs are certified in X" for marketing purposes
All that said...the exception to the above is the certs that do have some value. These are the certs that you have to pass a lab for: RHCE, Oracle Certified Master, Cisco's CCIE, etc. A CCIE is highly valuable - those guys bill very well.