Don't make the mistake of assuming that caulk doesn't expire. Though it lasts a lot longer than milk does—typically about ten years—both latex and acrylic caulks eventually do give out. So inspect your windows and doors, tubs and sinks, and anywhere else you (or the previous homeowner) may have caulked in the past. If you discover any sealant that has dried up and cracked, remove and replace it. After all, cracked caulk is little better than no caulk whatsoever.