Sometimes you cut a performer some slack -- like when 97-year-old blues pianist Pinetop Perkins unknowingly repeats a song he'd played earlier or when 15-year-old Justin Bieber tries to dance with his foot in a walking cast or when 75-year-old Glen Campbell shows up suffering from Alzheimer's.

You try a little kindness and notice that on Friday night at sold-out Mystic Lake Casino, Campbell filled the showroom with his smile, played some remarkable guitar in a variety of styles and exuded more positivity than Norman Vincent Peale.

Campbell's 70-minute performance on his Goodbye Tour seemed brave, misguided and sad. Actually, heartbreaking might be a more apt word. Oftentimes, he appeared confused, not knowing where to stand, which key to play in or what words to sing. He mangled lyrics, forgot lyrics and didn't even bother to consult the electronic prompters at his feet. He even struggled with the names of his band members -- including his daughter Ashley.

"You ever go inside a place," he said late in the show, "and forget what you want? It's fun but it's embarrassing sometimes. I'd rather laugh about it."

Campbell invariably had the right spirit if sometimes the wrong words on Friday. Sometimes he even found the right notes, voice and words and put it all together. Hank Williams' "Love Sick Blues" was playful and spunky as he almost yodeled like he was back on "The Glen Campbell Goodtime Hour," his popular TV variety show (1969-72).

Jimmy Webb's "The Moon's a Harsh Mistress" -- just Campbell's voice accompanied by the piano of T.J. Kuenster, his keyboardist for more than 35 years -- was a smooth croon, a comforting meditation on loneliness. That is what the crowd came for.

The fans couldn't have asked for more from "Wichita Lineman," another Webb gem, as Campbell crowed about being down on his luck but holding on, reassuring everyone with that final held note that he feels "f-i-i-i-I-I-I-ne." He received a hearty standing ovation.

Campbell's guitar work was consistently expressive and impressive whether on acoustic or electric. People don't realize that he was an ace session player heard on the Righteous Brothers' "You've Lost that Lovin' Feelin,''' the Monkees' "Daydream Believer" and Frank Sinatra's "Strangers in the Night," among other hits. On Friday, he got jazzy on "By the Time I Get to Phoenix," married flamenco and Western on "True Grit" and mixed jazz and twang on "Gentle on My Mind."

Campbell seemed lost on material from his new "Ghost on the Canvas," a poignant but not morbid collection. He didn't seemed invested in "Any Trouble," written by reclusive Minneapolis rock star Paul Westerberg. Campbell's own moody "It's Your Amazing Grace" had amazing sentiment, but it demanded U2-like passion, not unfocused resignation.

But, by the end of the night, Campbell seemed to rally. For a guy who earlier sang "I'm so afraid of dying" in 1969's "Galveston," by the closing benediction of his own 2012 tune "A Better Place," he was accepting his life and fate. "Some days I'm so confused, Lord/ My past gets in my way/ I need the ones I love Lord/ more and more each day," he sang, accompanied by three of his children. "The world's been good to me/ A better place, awaits you'll see."

See the set list at: Twitter: @jonbream • 612-673-1719