To elaborate a little on what Hoov is likely experiencing.
In the Central Oregon area they use crushed red lava rock on snowy roads, the main form of traction control. They typically dump this stuff in large quantities. Unlike other rock used for this purpose, the lava rock crushes down to smaller pieces, and a super fine red dust. That red dust gets everywhere, making a huge mess, and is especially bad once the roads clear up. It is not uncommon to be driving to/from the mountain at 65 MPH with all of this dust suspended in the air and being kicked up by the other 1,000 cars going to/from the ski area and sno-parks. To a lot of people, myself included, this dust is a huge annoyance and something you fight all winter long. Once it gets on stuff, it makes its way everywhere and is really abrasive. If you are not careful and wipe a side panel, speedometer, headlight, tunnel top, etc. you get a bunch of small scratches. Some people don't care, a lot do.
While I like the value Mirage trailers provide, this is disappointing. I have used a number of trailers, and have never had a problem with dust being ingested into the interior of the trailer - with or without vents.
I would also note that every new Mirage I have been around experiences some kind of "break-in issues", including very recent high-end custom-built trailers. The most common in my experience are electrical issues with grounding or connections to some feature.
I would hope this "dusting" is an isolated incident related to seals or something, but I feel Hoovs pain and I would not keep a trailer that did this either.
Hopefully their quality control and build practices continue to improve over time, but as others have stated I don't think they are there yet. If you want a bomb-proof trailer that you don't have to worry about, this may not be the best option. However, if you don't mind doing some work they may be a good value. YMMV
