NELLIE CUSTIS would have blushed.

Hanging on the wall with the rest of the entries in the 15th annual Woodlawn Plantation Needlework Exhibit, which opened yesterday, is a small, hand-stitched portrait of Snoopy - gasp - sitting on a toilet.

The show's organizers say it's the closest they've come to porno needlepoint. Unless, of course, you count Tab Hunter's entry in last year's show: Adam and Eve on a pillow, wearing nothing but fig leaves. It won "honorable mention."

"We used to get some awful things. We'd try to hide them in dark corners. But I think the entries get better every year," says Mrs. Charles Bolte, who in 1963 organized what is now the World Series of stitchery. She hoped to revive the needlework tradition begun at Woodlawn by its original occupant, Nellie Custis Lewis, who learned the craft from her grandmother - Martha Washington. Woodlawn, three miles west of Mount Vernon, now belongs to the National Trust for Historic Preservation, and all proceeds from the show go toward maintaining the residence.

This year, more than 1,000 entries ($5 entrance fee) were received from men, women and children around the world, competing for 41 sets of ribbons in separate categories, including clothing, quilts, pillows, furniture, rugs, counted-thread work, crewel, wall-hangings and miniatures from original designs or commercial needlework kits.

"A lot of people look down their noses at kits," Bolte said, "but we think the show should be 'inclusive' rather than 'exclusive'. After all, a lot of people start out with kits."

The topic came up during a spirited discussion over quiche and coffee with the show's judges - author and stitchery expert Erica Wilson, needlework authority Hope Hanley, quilt expert Phyllis Haders, director of the Renwick Gallery Lloyd Herman, the Smithsonian's Doris Bowman and Bolte.

What makes a good needlepointer? "Technique," according to Erica Wilson. "Beautiful, smooth stitching, to get those curves, to interpret. Quite frankly, I think you have to be an engineer." Or a doctor. "A lot of psychiatrists are doing neeldepoint," says Bolte. "I see them earning hundreds of dollars, sitting there stitching away."

And thanks to fat-fingered he-men like Rosey Grier, needlepoint is Not For Women Only. This year, the show received a sizable contribution from men, among them a suede vest embroidered by Tab Hunter. "They've always been doing it," says Wilson, "but they were terrified to admit it." Men have the option of being judged with men only, or with the women. "We've never had a man win top prize," says Woodlawn curator Margaret Davis. Why? "Because the women are better."

Aside from all that, is it art? "Yeees!" Erica Wilson shouted. Lloyd Herman disagreed. "It can be art. The craft is the technique, but art is the idea. If you worked on one of Erica's kits, it would be Erica's art. You just paint by numbers." Hope Hanley interjects, "It can be art, but it isn't always."

The professionals say they can usually spot a commercial "kit" design, but admit that in the past, a few entries marked "orginal" were not. "I guess they feel that after they've finished it, it becomes their design," shrugs Wilson.

The judges, who get nothing but "a lot of fun" for their services, tossed a few more bargelloed barbs at one another before settling down to their task. But not before Phyllis Haders, who had slept in the mansion the night before, told this story: "I was lying in bed and all of a sudden I felt this thing outlining my body, the shape. Maybe it was a ghost. It felt like someone or something was checking me out." Or the quilt. Nellie Custis wasn't talking.

Prize winners this year are: best in show, Alexander Breckenridge of New York City, who also won best entry by a man; Carol Perk of Fairfax, Va., best entry by a woman; Fifth Grade of Hollin Hills School, best junior entry.Fifth Grade of Hollin Hills School, best junior entry.