My Spellcaster can fix these with repario but I thought there was a way to do this via fabrication, handiness or one of the new Eco LifeStyle careers? In another post someone suggested the smog vacuum...
If you have Realm of Magic and your Sim is a Spellcaster, I think the Scruberoo spell might work. It does on furniture that has been struck by lightning or damaged in a fire.