Will a mattress be ruined if it gets soaked with water?

The local cable company was out at my house today and stepped on a sprinkler pipe in my attic which caused minor flooding through parts of the house and for water to pour from my ceiling through the lights, ceiling fans, sprinklers, etc. Our queen size mattress (all bedding & box springs) was soaked during it. The company is saying that the mattress will dry out and be fine so they won't replace it. I've heard that mattresses that adsorb that much water will not dry fine and will end up smelling. Right now that bedroom smells like mildew because of the carpet and I can't tell if the mattress smells too. Does anyone know if water does ruin a mattress?