That hazardous-to-your-health example illustrates how some things are more clear in retrospect. And by looking back at other areas of our popular culture, we can now see more clearly how far we have come—or not, as the case may be.

One realm in which our culture's "progress" is painfully evident is music. And I'll use a bit of my own history to illustrate:

I was hugely into pop metal in the late 1980s. (Full disclosure: I still gravitate toward guitar-driven music, but my taste in lyrics has changed considerably.) That decade stands as the high-water mark for a certain kind of glam rock. It was an age in which Aqua Net and spandex ruled. August 1987 saw the release of Def Leppard's Hysteria, which sold 12 million copies in the United States alone. That year also saw huge multiplatinum records from Whitesnake and Mötley Crüe, not to mention countless other hair-metal wannabes.

I mention these bands of my youth because, as unlikely as it may seem, they've all recently released new albums. And I thought it might be instructive to listen to their latest efforts to see just how far they, too, have come—then compare them to the music world of today.

1987 Rides Again
Sonically, all three represent 1987 reloaded. Cut-and-paste virtually any of the songs from these bands' latest releases onto their vintage albums, and they'd be right at home. Lyrically, Def Leppard is the only band that, perhaps, has matured a bit beyond its "Pour Some Sugar on Me" glory days. Sure there's still a predictable sexual double entendre here and there on Songs From the Sparkle Lounge ("Baby, baby, won't you give me a good time," Joe Elliot and the boys plead on "C'mon C'mon"). Surprisingly, however, the Leps also critique radical Islam (!) and ask questions about corrupt government officials.

Whitesnake remains, well, Whitesnake. The new tracks on ... wait for it ... Good to Be Bad are evenly divided between sappy ballads and raunchier numbers on which 56-year-old lead singer David Coverdale still goes on and on and on about his ability to satisfy the ladies. Track titles such as "All I Want All I Need," "Good to Be Bad," "Lay Down Your Love" and "Got What You Need" are pretty much self-explanatory. Syrupy songs about love across the miles ("So far away from you, my darling," Coverdale croons, "I'm coming home to your good lovin'") recall the band's 20-year-old smash hits "Is This Love" and "Here I Go Again."

The guys in Mötley Crüe, for their part, haven't matured or stagnated. A quick glance at the four stylized-yet-still-very-nude females intertwined in the shape of a cross on Saints of Los Angeles' cover tells us almost everything we need to know about how they've kept pace with our culture's devolution. As do song titles with abbreviated references to the f-word ("MF of the Year," for example). Likewise, the chorus to "This Ain't a Love Song" brags, "This ain't a love song/This is a f--- song." For good measure, Vince Neil tosses in some sexualized violence and twisted religious imagery as well.

The, um, motley result often feels like a contrived effort to convince fans that forty- and fiftysomething rockers can nastier than they were in their twenties. Because as bad as they were back in the day, even the Crüe didn't casually toss around the f-word and glory in supercharged sexual misconduct as freely as it does on Saints.

Bad, Badder, Baddest
Even more interesting, I think, is how yesteryear's bad-boy poster children compare to today's edgiest artists. Back in '87, Leppard, the Crüe and Whitesnake were considered among the most damaging music influences, lyrically speaking. In 1989, I sat through a Hell's Bells seminar critiquing the metal genre from a Christian point of view—and as a result tossed 180 albums in the trash. At the time, music from artists like these was depicted as nothing less than a demonic force belched straight from the dankest regions of hell. (Hence the seminar's title.)

That assessment seems almost quaint these days. No one is protesting aging hair bands whose lingering presence is more likely to stir up feelings of nostalgia or jokes about mullets ("Business in the front, party in the back!") and acid-washed jeans than infernal fear.

So what's changed? That may as well be a rhetorical question, because you already know the answer: the culture around us. Compared to the nihilism, rage, misogyny and despair that populates a lot of metal these days, these three bands almost seem positive by comparison. Ditto when we compare them to the artists whose songs have ruled the mainstream charts this summer. Two of the most popular hits have been Katy Perry's celebration of same-sex experimentation, "I Kissed a Girl," and Lil Wayne's "Lollipop," a exceedingly graphic salute to oral sex.

When we take an objective step backward, however, it's clear that new material from Reagan-era metal gods is hardly praiseworthy. It only seems so, relative to two decades of cultural and musical degeneration.

This is more than a little telling of how our culture slips and shifts quietly, without our conscious knowledge, with each passing year and decade. What's acceptable, popular and "normal" today would have seemed utterly shocking not very long ago. All of which makes paying attention to the music, the movies and the media we consume that much more critical. Because we have indeed come a long way, baby. And just like those glamorous cancer sticks in the hands of well-coiffed beauties, what we don't know is still slowly killing us.