Blinds are natural dust magnets. Over time it collects and even gets grimy. An easy clean up is by attaching a clean dryer sheet with a rubber band  around each end of a pair of tongs. Now clamp the tongs ever each slat and slide across. The sheets will collect the dust and grime and get into those hard-to-reach spaces plus the residue from the fabric softening sheets will create a dust-busting force field and leave behind a fresh scent.