Are your bathroom tiles brown between the lines? That is dirty grout. You can make it white again in 20 minutes.
Baking soda, vinegar, old toothbrush, spray bottle.
1. Make paste with baking soda and water. 2. Rub paste on grout lines with toothbrush. 3. Spray vinegar on top, it will bubble. 4. Leave 10 minutes. 5. Scrub again and rinse with clean water. Your tiles will look new.
Do this once a month. Always open window after bathing so tiles stay dry and clean longer.