I have some wide slat wood blinds, which are probably the same. I just use the brush attachment on my vacuum and go across them once a month. They get really dusty at the top and I just use a damp cloth followed by a dry cloth. So far, so good.

I do not have wood venetians, but essentially they are the same as wooden shutters. And we have those on our windows in MA. I also had them for about 10 years in my MoccasinLanding bayou house. In MA, we can open the windows for ventilation and so they get dustier than if you kept the house closed or air conditioned. But so far, those shutters, finished in a white satin gloss, wipe off very easily.

The ones I had at MoccasinLanding were also wooden, painted white, and had a satin gloss. I never opened the windows because we went straight from winter to summer (no spring) and that mean air conditioning. It took about 2 months before I noticed any dust on those.

I'd say that your experience will vary if they are exposed to the outdoors very often. And also, what finish you use.
Wider slats (like in plantation shutters) are easier to clean because there is a LARGER GAP BETWEEN SLATS WHEN OPEN.
Tiny slats make cleaning more difficult, IMHO.

thanks marti and moccasin. they are available in a wide slat and a thin slat but there is enough room inside the door jamb for the wide slat with room to spare. I think these may have a poly finish (it was over 105F here yesterday so i couldnt be bothered going to look at them in person) and they will get dusty. one of the french doors is open a lot and it does get very dusty around these doors.

I have wide-slat (2") walnut-finish wood venetian blinds in my LR and 2" ivory faux-wood in most of the rest of the house. Admittedly the ivory color of the faux-woods does show dust less than the walnut finish, but they also LOOK like plastic to me so I'm looking forward to getting rid of them when I can. I'm not one of those types who has to have every cleaning gadget and product, I'm all about the multitaskers, but I do love me some Swiffer dusters now that they have the long-handled version - takes maybe a minute or two to dust a blind with those fluffy babies, so whenever I dust I just hit the blinds too. If you don't let the dust build up a lot you don't have to wash them. We have a wicked dusty house too; since we don't have central AC windows are almost always open in the warmer months and the forced-air heating is awful for dust despite filters on the furnace and every vent. I always say "you can write your name in the dust but please don't date it!"