Why is my dashboard shiny and greasy after cleaning, and is that a problem?

A shiny, greasy dashboard usually means a gloss dressing or silicone-heavy protectant was applied. Besides attracting dust and fingerprints, a glossy dashboard can reflect onto the windshield and cause glare, which affects visibility. Clean the residue off with a diluted interior cleaner, then use a matte or satin protectant designed for dashboards if UV protection is wanted.