You're right about giving edges a good scrub, but I learned the hard way that even a tiny bit of moisture left there can ruin the seal. When I sealed my bathroom tiles, I scrubbed clean but didn't wait for them to dry fully, so dampness got trapped and it peeled in weeks. Now I use a hair dryer on low heat to make sure edges are bone dry before sealing. It's an extra step I never see in guides, but it's key for making things last.