We're actually just selling ours now. I originally convinced myself and the DW that we "had to have one" and after some early enthusiasm and use, it quickly got shuffled off to storage and was rarely used. Here are my new and improved reasons why I didn't use it after all was said and done.
*The 2 year warranty doesn't cover "wind damage".
*We live in the desert (Las Vegas, NV to be exact) and when the wind blows, it sometimes REALLY blows. That brings with it a lot of dust and debris.
*If you tightened the straps down too much, anything on the RV not padded with 6" of protection between the RV and the cover was liable to poke through. It took about 10 minutes to deploy and snug up the cover on a calm day.
*Prepping and padding it always took much, much longer. Too long to justify it in my mind.
*If you left the straps a little more slack, the wind would cause the straps to rub against the fabric and start to wear through the cover. Aggravating.
*I also started to see some early signs of growth (mold, maybe?) and a little softening where the cover contacted the roof corners (you have to pad all of those, too).
*We aren't slobs per se, but I always felt like you'd want to start with a crystal clean coach before putting the cover on due to not wanting any grit and grime to get pushed around under the cover. There may not be any basis in fact to that, it's just how I felt. We do wash pretty regularly, just not after each and every trip.
Having said all of that, we have had the following failures in the trailer that I think are directly attributable to the sun and heat out here:
*Both windows in the doors fell out of their mounts and had to be replaced. (Pretty sure that was due to heat buildup from leaving on those aluminized reflectors all the time, won't do that again by which I mean use reflectors OR replace the window mounts on my own)
*The rear day / night shade plastic mount recently melted (yep, melted) and fell down, so we replaced with a curtain.
*One of the wood cabinet doors just cracked and has a 1/4" gap running the width of the door (it really is a DRY heat).
All happened after expiry of warranty.
We always have a vent open, but when it hits 115+.......
Hope that helps?