Yuck, ours are the same way! The ppl before us NEVER cleaned them and then I dreaded it so a year later, like you, I have only cleaned the downstairs ones. Bad. I took a wet towel or ppr towels and wiped each slat and it took me forever too. What a pain! If you can afford it, I would hire a company to come in and do ceiling fans, baseboards, and blinds one time then you keep up with them. if you cannot, keep doing what you did, turn them all one way and try wiping straight across and working downward how they are turned. It might be a bit quicker than doing each single one. Then, once you get them clean, take the attachment brush on your vacuum cleaner and run it over them so the brush knocks the dust clean and sucks it in at the same time. Then, take a dryer sheet and wipe them down. That is supposed to prevent dust in the future. It repels the dust with its static electricity. I plan to read your answers and learn how to delve into my upstairs ones! I hate cleaning blinds and baseboards! :o)