There's a definite joy in watching bad, hilarious people do bad, hilarious things on FX's hit comedy It's Always Sunny in Philadelphia. It's hard to believe the Philly gang can do anything worse than when they got addicted to crack or kidnapped a Hispanic family and destroyed their home, but we can guarantee they will in the upcoming eighth season of the show. But at least the Sunny gang always means well, which is why creator Rob McElhenney thinks they've gotten away with the series for so long.

"We come at it from a character perspective in terms of motivation. We try to figure out what they would want and what means they would use to get there," McElhenney told Spinoff on the red carpet at Monday’s It's Always Sunny premiere. “So it's never, 'Oh, well, what's the most terrible thing we could see.' It's, 'What's something that someone on a CBS sitcom wouldn't necessarily get to do,' and then we try to do that."

Co-star and executive producer/writer Glenn Howerton reinforced that, saying the main characters work because they think they're doing good.

It's clear that Dennis, Dee, Mac, Charlie and Frank have changed a lot since It's Always Sunny in Philadelphia debuted in 2005. There's even an episode this season that refers back to earlier jokes, with the entire premise being a nod to "The Gang Solves The Gas Crisis." Howerton said that episode was thrown in as a wink to fans.

"That was the only episode where we sort of address where these characters have been,” he explained. “It was kind of, I guess, our version of a flashback episode in a way; revisiting some territory and retreading territory, but that was just something we did for fun.”

McElhenney added, "We never really evolve that much. You'll definitely see different sides to our characters -- that's just part of the fun of creating new ways to display our characters, but they'll be right in line with what you would expect from these people."

However, there are some physical changes this season. McElhenney's character Mac has dropped the weight he gained in Season 7, and according to Mary Elizabeth Ellis, who plays The Waitress and is Charlie Day's real-life wife, a certain someone is happy about that weight loss.

"I think Kaitlin's happy. He doesn't crush her at home anymore, you know? It's a good thing," she said, referring to McElhenney's co-star and real-life wife Kaitlin Olson.

Ellis was on the Sunny red carpet to confirm that her character will return this season. But, speaking of change, The Waitress is not the nice coffee shop employee we've known from earlier seasons.

"They do terrible things to me -- even more terrible than usual," Ellis told us. "I went and shot on my set this year of my apartment, which used to be like really cute and now it has graffiti in the hall. I'm turning into Charlie, I feel like. I don't know what's going to happen. Maybe we'll meet somewhere in the middle."

She added, "This year bodes well for Charlie. I'll put that out there."

While we won't be finding out the name of The Waitress any time soon, Ellis said there will be payoffs this season. Part of that is having characters like the McPoyles and actors like David Hornsby, Sandy Martin and Lynne Marie Stewart come back.

"It is fun, once you watch a television show for eight years, you really do get to know the people. As it goes on you're like I remember that and I remember that," Ellis said. "We loved The Wire, we watched The Wire, and then, like, in Season 4 when you start seeing things that happened in Season 1 and you're like, 'I knew it was going to pay off!' it's so exciting."

The cast wouldn't offer much by way of spoilers, but Howerton did confirm that we won't see a return of the D.E.N.N.I.S. system. However, there will be "different systems" that are "pretty ugly" and show the "evolution" of Dennis. Howerton also said we'll see Dennis degraded in new ways.

Ellis offered another tease of this season: the Halloween episode, "Maureen Ponderosa's Wedding Massacre,” which marks the return of Dennis's ex-wife Maureen Ponderosa. "It's as amazing as you think it's going to be," she promised.

With It's Always Sunny heading into Season 8, it seems fair to think the end might be in sight. McElhenney said it's not something they're really thinking about, and that the team will "keeping making [episodes] as long as people keep watching them."

"We'll do a couple more years," Howerton clarified. "We'll do a couple more years, and then we'll get out of here before people get totally sick of it."

The eighth season of It's Always Sunny in Philadelphia premieres tonight at 10 ET/PT on FX.