If there is anywhere in an old house where the thought bubble "It has character!" can quickly turn to the thought cloud "It could be condemned," it’s the bathroom. Years of use appear in extremely unsavory ways, from grout that never comes clean to cracked and pitted porcelain to running toilets that defy repair. Fortunately, the surge of interest in the bath as a spalike retreat within the home has resulted in a wide array of options for creating a bath with period good looks and contemporary performance. It's the renovation equivalent of a double take: Charming old mosaic floors, pedestal sinks, and tiled walls are gutted and replaced with charming new mosaic floors, pedestal sinks, and tiled walls.