If the blinds are plastic or metal and you want to leave them in place to clean them make a 50 50 solution of warm water and white vinegar in a bowl or bucket.
Cleaning metal window blinds.
This keeps it from spraying backwards and ending up on the blinds where it can attract dirt and dust.
Mix in a little mild dishwashing soap.
Wet a car washing brush and brush the blinds from side to side and then turn them over and brush the other side.
Put a few drops of dishwashing soap in a bucket of water.
Another preventative measure you can take is to always spray window cleaner on a paper towel or rag and never on the window itself.
Fill the tub with a couple of inches of warm water and add several squirts of dish soap.
For tough stains use a soft brush to scrub the area gently.
Remove the window blinds from the window and hang it from the hooks.
Finish by wiping each slat again with a sponge dampened in fresh clean water.
Take the blinds outside to your patio or driveway and lay them on a small rug or piece of carpet.