Eight years ago I wrote a column criticizing Jay Leno's transformation from family-style stand-up comic to raunchy late-night talk-show host, suggesting that while he was once one of the cleanest comics on the nightclub circuit, he had lowered his standards by peppering his "Tonight Show" monologue — and interviews and skits — with less-than-subtle sexual double-entendres.

To my surprise, Leno actually phoned me to discuss the matter … which made for another column but didn't really change my mind.

I've continued to watch Leno's late-night show from time to time and have seen no evidence — despite his protests to the contrary — that he's any less vulgar than my impression all those years ago.

In fact, I think he bears some responsibility for the lowering of the sleaze bar by commercial television in general and late-night comics in particular.

Sadly, at least from this corner, that seems to be Leno's most significant legacy as he departs late-night TV tonight and prepares for his new fall show, which will air at 9 each weeknight on KSL-Ch. 5, the local NBC affiliate.

Much has been written about whether Leno can sustain a nightly prime-time comedy/variety program, and whether the same show night after night (albeit with different guests) can compete with the other networks' reality shows and scripted fiction (all those "Survivors" and "CSIs").

Also interesting will be whether Leno's nightly use of big-name guests will have an impact on bookings for his "Tonight Show" replacement, Conan O'Brien — not to mention the rest of the already too littered talk-show landscape.

And not just David Letterman, Craig Ferguson, the two Jimmys (Fallon and Kimmel) and all those others on your night-owl radar, but also such daytimers as Ellen DeGeneres, Bonnie Hunt and many others. (Oprah Winfrey is immune, of course; she's in her own space-time continuum, where she'd have no trouble booking whoever she wants even if Leno was doing three hours of prime-time programming every night, including weekends.)

Having a show on more than once a week in prime time isn't unprecedented, of course. Those of us who are old enough may remember that in the 1960s, ABC had some success with half-hour episodes of both "Batman" and "Peyton Place" airing twice-weekly.

And in the 1960s and '70s, when variety shows were in vogue, you could watch a parade of guest stars all week long, singing and performing in comedy skits, much the way Leno is promising will happen on his new program.

During any single week of the 1967 season, for example, one could see many superstars of the day performing on "The Ed Sullivan Show," hosting or guesting on "The Hollywood Palace" and "The Kraft Music Hall," and appearing on such star-headlined efforts as "The Dean Martin Show," "The Carol Burnett Show," "The Smothers Brothers Comedy Hour" and "The Jackie Gleason Show."

But five straight nights each week with the same host is another matter. Leno could wear out his welcome rather quickly.

Still, I'm more interested in seeing how his raunchier gags go over during primetime, as opposed to late night.

Oh I know, primetime is lousy with locker-room gags already, especially in the few sitcoms that still dot the TV landscape (ABC is launching a bunch more in the fall).

But Leno's sniggering schoolboy act may not play as well BEFORE the news each night as it has after.

E-MAIL: hicks@desnews.com