Last few months I've spent looking for a case to serve me perfectly and there were a few but I struggle with paying +130€ for just a chassis since my hardware isn't up to date and I can't play the latest games on the lowest preset settings smoothly. So that's where I decided to not pay much attention to the look of the case anymore, now I sit here with my itchy finger on the purchase button of a Corsair 200R asking my self the question:
You can install the fans at the top which I won't, there aren't any filters so dust will come into the case just like this.
Will I have to clean the case more often from the inside or won't it make much difference for me to clean it more often?
Fractal Design Arc Midi R2...
Filtered everywhere, 3 fans included, should be under 100€... 
Zalman Z3 Plus...
Almost perfectly dust proof, comes with 4 fans by default, should be under 50€
To answer your question - whatever case you choose, you will have to clean atleast twice a year.
If the dust filtration is crap - even more often.
have a 200r, occasionally gets dusty, wouldn't recommend.
My suggestion is the Phanteks Enthoo Pro. I'm using it and it's a pretty good case. I think is a nice swiss army like case that can fit like any hardware. It's 84$ on Amazon (black windowed), has all dust filters in all the fan spots except for the rear exhaust, one 200mm fan in the front and 140mm in the back, PWM fan splitter and a nice build. The only gripe is the fragile window that scratches a bit easly. Other than that I think is a pretty good value for the money.
I would always recommend the Fractal Design Arc Midi R2, being a proud owner myself. Such an easy case to work with.
if you setup your top fans for exhaust you should be fine
Alternatively, get a thin sheet of rigid material (wood, metal, acrylic, et cetera) and cut it to shape. A couple screws later and you'll have the top fan mounts taken care of.
Every Zalman case I've worked on has had a defect and I know my boss is in the process of taking them off our product list. They aren't worth it.
On the topic of the 200r... meh? It's a case, it feels cheap it does computer case stuff and yeah it's gonna get really dusty. It isn't bad for the money just not fond of it.
Nice
Was just my way of saying there's nothing wrong with the building/functionality (other than if you cable manage like an amateur GL closing the panel) but there's also nothing that made me say "this is nice"
Owner of a 200R for 5+ months. I got it for less than $50 USD. The top definitely has no filters whatsoever however I only had to clean the outside of the case once and I will say it is in a basement that can acquire dust easily. I can't comment on the inside though because I haven't bother to check (I probably should) however I doubt you will have to clean it often. Maybe once per 6 months which is normal anyway.
Case is fine if you can get it at the same price I did however there are better mid-tower cases out there if you have the cash to pony up.
i have the 400r, and im pretty happy with it. it has a whole lot of fans slots and keeps the system cool. i do clean it out like 3 times a year or so. it has a handhold at the top and a few more fan slots then the 200r but is otherwise pretty similar. also even with dust filters, you still have to clean out the dust filters. 130 euros is a lot of money and i'd go with this
over the 200r, but if you could get the 200r cheap it's not a bad choice.