Naughty Marcella is always trying to brush off her guardian angel--no protective presence but a tiresome voice of conscience who mutters RUDE! STINGY! MESSY! on appropriate occasions. She also barges in while the little girl is crying alone over the crummy gifts she received for her birthday. But then she suggests that Marcella play a game called Flip-Flop--""turning yourself inside out every other day,"" as in happy-sad, good-bad, and so on. And that does it. When Marcella starts to push ahead in line next day she thinks RUDE-POLITE and goes to the end. . . DIRTY-CLEAN and picks up her gum wrapper. . . and, feeling stingy, she shares her ice cream, skateboard, jacks and ball, and ""even"" her spyglass. It's a total flip all right, but no less contrived for the gimmicky game. PREACHY is the word for Marcella's Guardian Angel, both the figure and the book.