Writer Ken Mandelbaum's "Not Since Carrie" is an informative and highly readable book full of mistakes - mistakes, that is, made by producers, directors and writers who put their talents, energy and money into Broadway musicals that flopped.

Mandelbaum, a columnist for Theater Week magazine, pegs his book of failed shows on "Carrie," the 1988 musical based on the popular Stephen King horror novel and subsequent film. Soon after it opened on Broadway, "Carrie" - as "Breakfast at Tiffany's" and "Kelly" had done before it - became synonymous with "Broadway musical disaster."It apparently deserves such distinction. Mandelbaum sees "Carrie" as unique in the history of Broadway musical flops for "its combination of soaring, often breathtaking sequences and some of the most appalling and ridiculous scenes ever seen in a musical. It alternately scaled the heights and hit rock-bottom."

One of its more memorable numbers came in Act 2, "Out for Blood," a pig slaughtering set to music that left most onlookers in silent shock.

Broadway flops "exert a perverse fascination" to lovers of musical theater who are "often more eager to discuss a show that played for three performances than one that played three thousand," Mandelbaum writes, adding that "total calamities have a morbid fascination; fans relive them and ask, `How come these people didn't know better?' "

The nearly 200 musicals discussed in the book are limited to those that opened since 1950. Instead of placing them alphabetically, chronologically or as though their names were plucked from a hat, the author sorts them into categories, among them "Star Flops," "The Movie Was Better" and "Not Bad."

Although a failure offers a wealth of opportunity for a critic to sharpen his claws and display his sarcastic skills, Mandelbaum avoids that route. More often, he writes with a degree of awe for the many cases in which Broadway veterans with hit shows to their credit could not recognize the bomb they had created.

He also mourns failed projects that had positive qualities - endeavors such as "Do I Hear a Waltz?" and "House of Flowers," and particularly "The Golden Apple," about which he writes: "Most of the shows in this book failed their audiences; it was the audience that failed `The Golden Apple.' "

To the people involved - investors who lost small fortunes, and artists who suffered embarrassment, frustration and disappointment - a Broadway flop is serious business. Nevertheless, in their failure, some of these shows produced unintentional comedy, and Mandelbaum delightedly shares such tidbits as:

- At the opening of "Reuben, Reuben" in 1955 in Boston (it never reached New York), the audience was so bewildered by the goings on that at least 300 of them had left by the second act, and many who had stayed talked back to the actors on stage.

- The 1981 sequel to the popular "Bye Bye Birdie" was called "Bring Back Birdie." At one of the show's four Broadway performances, star Donald O'Connor "forgot the words to his song `Middle-Aged Blues,' asked the boys in the band for help, and then said, `You sing it. I hated this song anyway' to gasps from the audience."