I just had tile floors installed in my bath and kitchen. One of the contractors said that they don't need sealing because the grout had seal in it. I never heard of this so would appreciate any insight.
We'd need to know who the grout manufacturer is and what product he used. There are "sealed" grouts and additives out there but I prefer to manually seal the grout with what I know is a quality product.
With any sealer, bear in mind that it doesn't make it waterproof or stainproof...it only makes it easier to clean and stains don't "set" readily.