Join CAP because you want to participate in CAP programs, not because you want another bullet point in your extracurricular activities section. My understanding is that those who will be reviewing your application are looking for dedication to and leadership in your activities, not just a check in the box to make you "look good." While you are not technically too old to join as a cadet, you are not likely to get much more leadership experience in the year (or less) until you're sending in that college application than the twelve-year-olds who would be joining at the same time as you.
As in any organization, there are tools who make the rest of the members look bad; the thread to which Mumbles linked shows some wincingly bad ones. That said, such has not been my personal experience--I've been lucky enough to work with people who comport themselves with professionalism and good humor (actually, a good number of them are retired Naval Aviators and NFOs). Bonus: I have had more flight time with CAP since I started volunteering with them last year than my husband has since getting winged in April '08, but I think that says more about how backed up the COD pipeline is than how much CAP gets to zoom around in our sweet Cessnas.
Mmlz, your real answer is right here: if you will "fill [sic] stupid" participating in Civil Air Patrol, what makes you think you would be capable of making yourself "look good" in such an environment? Everyone would be better served if you found an activity more suited to your interests. If your only interest is finding an application space-filler, though, you might have a difficult time.
Good luck,
Annalisa
2d Lt, CAP
