ST. LOUIS — At 88, blues guitarist B.B. King is a living legend, a Rock and Roll Hall of Famer with his own satellite radio channel and a string of blues-themed restaurants in New York, Las Vegas and several other cities.

Slowed by age and infirmity, including diabetes, King continues to tour — with sometimes painful results. In St. Louis, some fans are singing the blues after an erratic weekend performance led to a stream of audience catcalls and early departures.

Concertgoers said King’s rambling Friday night set at the Peabody Opera House featured just a handful of complete songs amid meandering musical snippets, long-winded soliloquies, an 8-piece backup band that missed its cues and a 15-minute sing-along of “You Are My Sunshine.”

“Is he a living legend? Absolutely. Do I love his music? You bet,” said digital marketing executive Larry Goldstein, who paid $150 for a pair of tickets plus parking. “But when you’re paying that type of money, you expect to see a show.”

The experience at King’s concert highlights an increasingly common occurrence as musicians in their 70s and 80s take the stage in front of nostalgic audiences. A recent St. Louis concert by 87-year-old rock ‘n’ roll pioneer Chuck Berry was also marked by missed chords, forgotten lyrics and a backing band’s persistent efforts to cover Berry’s missteps.

St. Louis record store owner Tom “Papa” Ray did not attend the King concert, but said audiences should know to adjust their expectations when watching beloved musicians whose peak is well in the past.

“If your 88-year-old father or grandfather was great in a particular art or craft, and his performance was disappointing, would you heckle him?” said Ray, owner of Vintage Vinyl. “It totally saddened me to hear about that.”

Brad Goodman, King’s Los Angeles-based agent at William Morris Endeavor Entertainment, declined to comment through an assistant. Peabody Opera House executives and King’s Las Vegas promoter did not respond to multiple interview requests.

Other recent King performances have also struck sour notes. During a November concert in North Texas, the bluesman’s voice “was weak and ragged, and his trademark guitar style had dissolved into a parade of sour notes,” a Dallas Morning News review said. Bob Johnson, a retired IRS agent who attended the St. Louis concert with his adult daughter, said the dissatisfied audience members were trying to encourage King more than criticize him, suggesting specific song titles or urging him to “Play some music” during the long interludes.

“Everybody was trying to be respectful that this guy is 88 years old,” he said. “It was painful to watch.”