Why does my interior plastic feel sticky?

Stickiness usually comes from the breakdown of soft-touch coatings or plasticizers in older interior plastics, accelerated by heat and UV exposure. It can also come from heavy dressings or cleaning product residue. Residue can be removed with a suitable interior cleaner; true material breakdown is much harder to reverse and may require removing the degraded soft-touch layer or replacing the part. Test any cleaner on a hidden area first.