They live through a lot of things nobody should.

Second film has a scene the entire family is about to get a makeshift electric chair but they manage to avoid it at the last moment for reasons however it probably wouldn't have done anything to them in the first place. The whole thing is a murder attempt by Fester's new wife so she can then claim his life insurance because the Addams family is extremely rich, which was a plot point in the first film, too. The wife, literally known as a black widow serial killer, already tried to kill Fester several times earlier in the film including blowing up the entire house Fester was sitting in with a bomb she gives him wrapped up as a present. Fester being Fester even manages to figure out the present is a bomb after shaking it, listening to it, and trying to guess what has been wrapped up. And the fact it is a bomb doesn't actually concern him because he still walks out the smouldering ruin after it explodes with little more than dirt and destroyed clothes to show for what just happened.

The rest of the family are similarly impervious to damage and invariably voice their jealousy of the others when they get to be the ones strung up on a torture rack while also using the moment to reminisce about honeymoons or other romantic endeavours.

Kinda iffy, they are alive enough to have kids and family but also somewhere on the ghoul scale