Home Improvement Questions? Ask a Handyman for Answers
My thoughts on grout sealer are that it's a complete waste of money. It really doesn't do anything other than create a profit center for tile product suppliers. It won't stop the lines from darkening up since that's entirely due to dirt. And it won't effectively prevent stains. We've been installing tile on our jobs for over 50 years and we never use sealer and we've never had a complaint.
Let me know if you have more questions
The grout is going to get dirty. However that happens the easiest way to get it back to it's original light color is to use gel type toilet bowl cleaner with bleach. You squirt it on the lines let it set for 15+ minutes then wash it off.