Here’s something I wrote in 1998 or 1999 or so.
I’ve always been kind of fascinated with how these little backmasking scares appear to come in cycles, particularly when there’s some perceived “moral crisis” in the country. As priest confessors, Grand Inquisitors, Puritans from Salem, Kenneth Starr and Manoling Morato illustrate, those most obsessed with sex (or Satan) are the same ones who’ve taken it upon themselves to ferret sex and Satan out. Too much time on their hands, I’d say, when there are genuine social concerns to address.
Granted, subliminal images in advertising and films are fairly well-documented. There were rumors in the ’60s (during the Cold War, a good panicky time) that there were subliminal advertisements underneath the Muzak played in supermarkets to encourage shoppers to buy certain products. But to lead someone to worship Lucifer??? Give me a break. It’s a very anti-humanist view of people for Christian pastors to adopt, I’d say, taking the metaphor of “their flock” too seriously…
One of the guys in my high school was utterly obsessed over backmasking and the connection between rock ‘n’ roll and Satan that he ultimately wrote a 100-page paper for a Social Science class about it. Essentially the guy, fueled by his newfound born-again Christian fundamentalist faith, combed through back issues of Creem and Kerrang! or whatever and picked out various anti-Christian/anti-status quo quotes, of which there were many. The local Catholic church was so impressed with his research that they invited him to give a two-part lecture at the local auditorium. 
In any case, the highlight of his presentation was the result of painstaking backmasking; Cool Edit didn’t exist then, so he must have cracked open all those tapes and physically turned the loops over. Unbelievable! Anyhow, everyone was given a handout with all the evil lyrics they were supposed to hear, thus setting the stage for a more receptive audience.
First up was Depeche Mode’s “Master and Servant” — the part in the beginning where the vocals go “It’s a lie / it’s a lie” was supposed to sound like “God is cheap / God is dead.” “Turn me on dead man,” from “Revolution No. 9,” was reinterpreted as a reference to Satan. Anyhow, he went through a whole range of songs — Tears For Fears’ “Shout,” “Stairway to Heaven,” and “Hotel California” (boy did he have a field day with that one), but I can’t remember the exact words we were supposed to hear. Most famously was the “Start to smoke marijuana” phrase supposedly heard during Queen’s “Another One Bites The Dust.” (This was “clearest” during the chorus “breakdown” just before the end, when Freddie Mercury kept reciting “Another one bites the dust” over handclaps.) Though the backmasker couldn’t exactly explain the significance of the backwards message in Prince’s “Darling Nikki” (off the album “Purple Rain”) — it went something like “God is coming soon” — so Enrique (our backmasker’s name) chose to focus on the sexual lyrics instead.
Actually, the highlight for me was when he showed huge slides of black metal album covers. The look on the nuns’ faces was priceless.
 Satan and sex happen to some of the constant bugaboos in urban folklore, e.g. the supposed giant phallus on “The Little Mermaid” poster, the supposed “666” in the Procter and Gamble logo, etc.
 This happened to be a particularly urban folklore-fertile period (1988 or so) in the Philippines as well, which saw the country in the grip of a Satanism scare. Church groups were handing out flyers on “How to Spot a Satanist” — the anarchy symbol, the pentagram, 666, etc. The same flyers would warn of punks with mohawk haircuts defacing grave stones *and* distributing LSD-laced stickers to school kids (a nice conflation of urban myths right there). Needless to say, everyone distributed by the Twisted Red Cross label were highly suspect…
 (Obviously the way it works is through the power of suggestion: if you’re consciously looking out for “evil” lyrics, then garbled vocals will sound like what you want them to sound. The brain, in an attempt to find coherence in distortion, automatically tries to isolate and combine phonemes without the presence of a template — and if that same template (with all the evil lyrics) is already presented to you, then hey! it works.)