At the end of a decorating job, sort the covers before putting everything in the same bag. Unused packaging, a clean sheet and a sheet marked with paint are not necessarily handled in the same way.
Separate the materials
Keep cardboard packaging apart from the plastic contents. Check any material markings and retain the product information long enough to answer questions about disposal.
A recycling symbol or a known polymer name is not a guarantee that a local collection accepts a used decorating sheet. The collection method and the material's condition both matter.
Recycle Now explains that some plastic bags and wrapping can be taken to collection points, with local checks and clean-material requirements. Its packaging guidance does not itself confirm acceptance of paint-contaminated dust sheets. Recycle Now plastic film guidance.
Ask about the actual item
Use your council or waste contractor's current guidance for the item you have. Describe it as a plastic decorating dust sheet and mention paint, adhesive or other contamination. Do not describe it simply as a carrier bag because both feel like flexible plastic.
For business decorating waste, check the route used by the business rather than assuming a household collection point is appropriate.
Keep the decision practical
Reuse is an option only when the product permits it and the sheet is still suitable. Recycling is an option only when the receiving service accepts that material in its current condition.
Avoid washing paint into a drain to make the sheet appear cleaner. Follow the paint supplier's disposal instructions and the waste service's acceptance rules.
Before the next project, use what you learned to plan the number of sheets more accurately. Opening only the covers needed for the current stage can leave the remaining sheets clean, identifiable and ready for later work.