SOMETIMES THE MOST revealing social statements come in unpretentious guise. ''I wouldn't pay $12.95 for spaghetti if they had Mr. Chef-Boy-Ar-Dee himself in the kitchen,'' Roseanne Conner shrieks to her family during a rare outing at a fancy restaurant. This episode of ''Roseanne'' appeared last year, during that up-and-down phase of the ABC show when the heroine owned a luncheonette; that is, after she stopped working in a factory but before she became a millionaire by winning the lottery.

Looking back over the show's nine-year run, which ends on Tuesday (with an hourlong special that starts at 8), the Chef-Boy-Ar-Dee episode, ''The White Sheep of the Family,'' is an obvious high point. It is a marker that helps chart the evolution of the hit series from the jolting working-class truth of its early days to the pseudo-working-class chic of the last year. And it suggests how ''Roseanne'' flourished by addressing close-to-the-bone issues, dragging them into mainstream consciousness. By doing that, the show had an impact even on people who never watched it.

In ''The White Sheep of the Family,'' Darlene (Sara Gilbert), the smart middle child, turns down a job in advertising that pays $500 a week, choosing to finish college instead. It is an astonishing decision for someone whose mother thinks, You can dress it up and call it pasta, but it's still not worth $12.95. By the end of the episode, it is clear that Roseanne and her husband, Dan (John Goodman), feel threatened by the idea that one of their children will outpace them. When Darlene makes her typically sarcastic remarks about the Conner household -- with its afghan flung over the back of a shabby sofa and its constantly bickering family members -- it seems that their own daughter has become a snob. ''It's like you're one of them and you're putting us down,'' Roseanne says.

''Maybe I'm a little jealous of you because of all the stuff I had to do in order for you to get there, like working in beauty salons and restaurants and factories,'' she tells her educated daughter. ''But the good part is that I was able to give my kids better than I had.''