FOR THE PURPOSE OF THIS column, I will be playing Brian Lowry, a witty, urbane, sometimes caustic critic for a trade newspaper. Think George Sanders in “All About Eve,” with a boyish pinch of Redford circa “All the President’s Men.”

That’s not really me, of course, but it’s a version of me, which has become an increasingly popular trend lately, especially in the rarefied world of cable comedy.

This week marks the arrival of “Unscripted,” HBO’s latest blurring of real and fictional characters, an experiment tried with considerably less success in the Washington-set hybrid “K Street.” The entire channel, in fact, is awash in people playing themselves, from Larry David’s curmudgeonly “Curb Your Enthusiasm” to the celebrity cameos in “Entourage,” another insider’s guide to Hollywood.

Moreover, other networks are tapping into this vein, including Showtime’s upcoming Kirstie Alley series “Fat Actress,” which features the one-time “Cheers” co-star playing an unflattering (and at several moments, uncomfortably embarrassing) version of herself. Among the show’s several cameos, NBC TV group chief Jeff Zucker does a creditable job as Jeff Zucker, though based on the script, he has never seen a woman before who weighs more than 110 pounds.

Everyone is so busy playing themselves you wonder if anybody has time left over to actually be themselves — assuming they can still differentiate which is which — or if these actors remember how to play somebody else.

Granted, none of this is especially new. Hell, in “Sunset Blvd.,” famed director Cecil B. DeMille appeared as a rather sympathetic incarnation of Cecil B. DeMille, taking pity (though not too much) on aging Norma Desmond, or was that Gloria Swanson? Viacom’s Leslie Moonves also pops up as himself periodically (from “The Practice” kidnapping to his “Arli$$” cameo), continuing Brandon Tartikoff’s proud tradition of hammy execs.

What remains a mystery is the upside in all this, and who between Manhattan and the Pacific Palisades is supposed to care. In “Unscripted,” which focuses on struggling actors capturing their lives as really struggling actors, I wondered how much poorer the viewing experience will be for those unable to appreciate the cheap “Hey, I know that agent!” or “That’s George Clooney’s publicist in the background!” thrills that I enjoyed.

For HBO, perhaps, the street cred these series engender within the creative community offers its own currency, but the proliferation of such programs threatens to become more about self-obsession than entertainment — what the late monologist Spalding Gray called “creative narcissism.”

It’s also puzzling that showbiz folk are so eager to portray themselves as complete boors and boobs. Sure, it was hilarious on “The Larry Sanders Show,” and it’s a way of looking like a good sport. Still, with President Bush regularly delivering a Hollywood-bashing applause line during his re-election campaign, does it make sense to reinforce the industry’s worst stereotypes?

On one level, these harsher images doubtless prove liberating for celebrities — a chance to cut loose and acknowledge that they are less than perfect or heroic. It’s the antithesis, in a way, of bogus red-carpet pleasantries and the inane patter that fills talkshows, complete with softball questions teed up to trigger pre-approved anecdotes.

At some point, though, as fiction swallows reality and vice versa, the denizens of this image-conscious town must consider what it means to erase boundaries that establish where the show begins and, just as significantly, where it ends.