For dull, lifeless-looking grout on your bathroom tiles due to mold and mildew spray some shaving cream on the grout after you shower. Let it sit for at least 10 minutes then wipe off with a damp cloth. The steam from the shower will have loosened any gunk and the alcohol in the shaving cream will break down the mildew. Tip within a tip: buy shaving cream for this purpose at the Dollar Store!