The answer to 'tile and grout cleaning smells bad' is that a foul odor after cleaning tile and grout is often caused by bacteria or mold growth. This can happen if the grout wasn't properly sealed or if there is excess moisture trapped in the porous grout. The smell may also be from the cleaning products used, especially if they contain harsh chemicals.
To fix the problem, you'll need to thoroughly clean and disinfect the tile and grout, then make sure the area is completely dry before sealing the grout. In some cases, you may need to replace damaged or crumbling grout. If the smell persists or the issue keeps coming back, it's best to call in a professional tile and grout cleaning service.