It’s a little past midnight at HSN headquarters, and Serena Williams is nine minutes into a disquisition on a piece of fabric she’s called “Convertible A-line Top With Scarf,” available to you, the home shopper, for $39.95 or three “flexpays” of $13.32. “It’s like one huge circle that has a lot of style in it,” she says, not without conviction, fiddling with the bottom of the one she is wearing (“This is, um, mustard”), flapping it like a fan, rubbing one hand on her arm, and smoothing her hair. She forgets the names of colors, misstates a price. There with the right number and the right name is HSN savant Bobbi Ray Carter, sheathed in a hot-pink Convertible A-line Top With Scarf and raccooned in black eyeliner, filling in her co-host’s “ums” with the deft patter of a sales professional: “Amazingly transitional, think-fall-think-summer-think-winter-summer-into-fall versatility, quality, surprise scarf.” Bobbi Ray Carter knows how to touch a piece of fabric: She gives it a crisp snap between her fingers, smartly smooths the drape, all the while growing progressively more tense as Serena fumbles some hangers and launches, at 56 minutes, into a long anecdote about packing jeans for Wimbledon. “Mmmm,” says Bobbi Ray Carter, tight-lipped and possibly not breathing, awaiting the arc of Serena’s story to make its mumbly descent — “I felt good packing my own jeans, I had a moment there” — so she can finally change the subject — “And it’s our customer pick!” — and steer us back to the safe harbor of Denim Moto Legging color choices.