I actually had worse problems in my rack lol. I've never had respiratory infections in any of my critters, but their humidity had been too high and my bp ended up with some sort of scale rot? I'm not really sure in all honesty, but it went away after I bought these cages. It's like the top part of some of his scales started to flake away. But it went away once he moved and had a couple of sheds. I don't cover all of the vents, the ones in the front for the lights are not covered. I just cover the one over the uth. Either way there is more ventilation than in some other cages like boaphile or even some tubs. BUT that's a whole different story. My ball looks extremely bright now that he is in his showcase cage, it's like he looks as shiny and good as he does when he sheds, but it's 100% of the time.
I can definitely understand having to wait a while to afford a new cage! I too am waiting to get my next cage until I have some money. I just spent a bunch on building a cage and a lizard lol. I do have to say that I like the zilla critter cages, and if I had to get tanks again I'd go with them (mostly because I LOVE their tops).
OH and I forgot the other nice thing about these cages is that they came the exact same week I ordered them lol. And the 4 foot cage probably weighs as much as a 20 gallon tank. They're SUPER light. Which is nice for me since I'm tiny :x