Here's a list of things why candidates have failed:
Do you know what we do?
Did the candidate google us and find out what we do? If he/she has, that shows that the person has taken the time to try and see if he would fit into what the company does.
If the job requirements say a CWNA is the minimum cert, then yeah you need to have a recent cert or at least be able to answer simple, basic questions about 802.11. If you can't answer what the difference is between a bssid and an essid, then you shouldn't be applying for the job. What the ideal candidate would have done is read through his CWNA book to refresh his memory on some of the topics.
If the job requirements say you need linux experience with the command line and logs, then even if you don't have vast experience, you could always join a local or online linux user group, or use linux at home and be able to tell the interviewer more than "ls" when asked what commands you know. If the candidate had taken the time to spend 1 friggin hour with an online linux free command line tutorial, he would have been able to answer basic questions. The ideal candidate would have looked up "search linux logs" and known about grep, more, pipe and maybe even sed and awk. If you want the job then you have to realize that's what you're going to be doing most of the day and the ideal candidate would have known that if he researched what the job would likely entail and would have known at least one grep option.
If the job requirements say sql experience, at least know something about it. Once again, one hour with a free online tutorial would have passed the interviewer's questions.
I guess what I'm saying is, if you want to pass an interview (even if you don't have a lot of experience) then at least come prepared. You prepared for all those certs you have, why not prep for an interview?
The company will list their job requirements and wish list in the job posting. Pay careful attention to this list. Google all the items. If you don't know a subject at all, then at least google it so you can say " I don't know anything about subjectXYZ except ....". Be honest. Tell them what you do know and what you don't know.
If you can ace some parts and know a little about the others on the wish list, you stand a good chance of getting the job. Spend an hour on each of the items in their wish list and not only will be smarter for it but likely have a better pay check.