Generally speaking, it's a workmanship and design issue.
Screws rusting because they're not stainless steel, design elements that simply don't work as they should (presumably because they reuse previous technology and design without detailed testing), models that show up for sale one year, and disappear entirely the next year (limiting repairs and spare parts), crooked sewing on seams that get very close to the edge of the seam tape, or miss the seam tape entirely, easily jammed (cheap) zippers, zippers that don't (and can't) match up smoothly such that you don't get ulcers and a full body workout every time you use them ... I'll stop there.
I enjoy using my CVT (even though my model disappeared after what seemed like only a year) and will continue to use it until it wears out. It serves me well, and I'd take it anywhere.
It's important to note too that the buyer pays anywhere from 1/3 to 1/2 the price for one of these Asian made tents when compared to an Australian or South African tent ... so it's also fair to say that a guys expectations should also be adjusted accordingly.
Perhaps most important to note in this type of discussion is that my CVT doesn't leak at all, and stands solid in heavy winds ... so it's really a matter of rusting screws and design elements that don't work as they should - and how much that might bother you when the CVT's lower price is taken into account.
BUT ... my first CVT rooftop tent purchase will also be my last CVT rooftop tent purchase, as my next rooftop tent will be a Howling Moon or Eezi-Awn, for which I'll gladly pay the premium - and adjust my expectations upwards accordingly.