How do I stop my kids from licking dirty things around the house?

They'll outgrow it. Toddlers and babies often experience the world by tasting it. This is normal behavior. The most important thing when you have children this age is to make sure anything toxic that they might put in their mouths is either out of reach, locked up, or preferably both. This includes any household product that's scented...If it smells good it will be eaten....Or any small objects like batteries etc.