It's not the first 5 seconds, it's the first few minutes. I assumed from that wonderful opening that the rest of the podcast would follow suit. First impressions and whatnot (and past experience with these podcasts). I am 33, not 13. Fart and dick jokes don't make me laugh anymore.
The Gunbuster podcast was quite good, and the FLCL was pretty decent. CDX can and has done some really fun, really solid podcasts. And as an adult listener, the juvenile humor that pops up on some of them is a bit of a turn off for me. I'm not ripping them personally, I don't have any sort of agenda. Just want to give them a heads up and my two cents.
Good or bad, I try to leave feedback when I listen. I don't imagine they'd post forum threads otherwise.