The answer to 'why is my countertop greasy' is that there are a few common causes, including cooking oil residue, soap scum buildup, or a chemical reaction between the countertop material and cleaning products. Greasy countertops can be a symptom of improper cleaning or maintenance.
Grease and oil can accumulate on countertops over time, especially in kitchens where a lot of cooking takes place. Soap scum can also leave a greasy film if not properly rinsed. Additionally, some cleaning products may interact with the sealant or finish on the countertop, causing it to appear greasy.