Charlie Sheen crumbles during the opening night of his 20-date tour at the Fox Theatre in Detroit.

Some came out of solidarity, some came for the spectacle. Most came for both and saw no contradiction in that.

On Saturday night Charlie Sheen kicked off his tour, Sheenishly titled "Violent Torpedo of Truth/Defeat Is Not an Option," in Detroit. But that latter statement proved to be over-optimistic, and what torpedoed were the remnants of Sheen's once-impressive career.

Sheen's image has always been that of a bad boy, both on and off the screen. His misdemeanours over the years – shooting a fiancée in the arm, drug overdoses – were seen by his fans as proof of Sheen's adorable naughtiness. His hugely successful TV show, Two and a Half Men, for which he was paid almost $2m an episode, mined this reputation with his character, the wittily hedonistic, Charlie Harper. Since his very public falling out with the producers of the show earlier this year, Sheen, a once-skilled comic and character actor, has thrown his energies into giving rambling interviews, full of talk of "winning" and "tiger blood".

His father, Martin Sheen, interviewed on Radio 4's Desert Island Discs on Sunday, said his addict son needs "help and sympathy". Both were in short supply at the opening night of his show.

It was both poignant and appropriate for the former A-list Hollywood star to begin his sell-out tour in Detroit. Now less of a city and more a symbol of the death of American industry, this former hub of car manufacturing is dying. Last week, the US census report revealed that Detroit's population had dropped by a quarter in the past decade and the city's mayor was reduced to begging for a recount in the hope of bringing it up enough to qualify the city for increased state and federal aid.

Whether Sheen's appeal now lies in what some see as his aspirational lifestyle or simply voyeuristic rubbernecking is something of a fuzzy issue.

Jason Proventher, and Jack Green, both 23 and from Michigan, were quick to pinpoint why they had come: "I'm here to see him fall apart," said Green. His friend added, "He's living the American dream!"

Is falling apart the American dream?

"No," said Proventher. "It's the ride up to it that's the dream, the fun part."

"He's awesome!" cried Jeff Strasche, 36, from Detroit.

Were the rambling webcam videos Sheen recently put up on the internet awesome?

"No, those were kind of weird. But this is going to be awesome!"

Inside Detroit's sold-out 5,100 seat Fox Theater, the concession stand was doing a healthy business selling unhealthy items, including $35 T-shirts proclaiming "Bangin' 7gs", referring to Sheen's professed former drug intake, and a $25 hat that informed onlookers "I'm not bipolar".

When Sheen appeared on stage, 45 minutes late, he had the smile of a Halloween pumpkin, his mouth full of shadows where teeth had once been.

Things started well for him. His sneers at his former show, Two and a Half Men prompting cheers from the audience. But when he spoke, it was a mix of incoherencies and vitriol: "I used my power against them and stuffed their arms down their gaping throats. No time to take their stinking toupees because this warlock was on the move!" he bellowed.

"Smoke some more crack, Charlie!" someone shouted. The underrated Joaquin Phoenix 2010 mockumentary, I'm Still Here – about a Hollywood star who suffers a mental breakdown and is bullied by the public – suddenly looked shockingly prescient. Heartbreakingly, clips of Sheen from Platoon and Wall Street played on screen while Sheen himself stumbled about on stage. He tried to show a film he made in the 1980s with Johnny Depp, but the boos prompted an early end to that.

"Maybe it's more appropriate for me to tell some crack stories," he said.

The audience cheered.

"What do you want me to talk about?" he asked a member of the audience.

"I want to hear about the porn stars!"

"Why do you want to hear about that?" he asked, disappointed.

It was a classic misunderstanding: he thought they loved him for his fearless honesty; they did, but only in regards to his intake of crack and porn.

"OK, OK, I'll do some crack stories," he relented, desperately.