I have to agree with both - to a point!
Yes, warm sectors can produce fog and mist, it's thick fog here now. But warm sectors & cold sectors can both produce excellent visibility, the lighting for each is quite different. You have the steely blue of a sunny colds sector, it looks cold & the contrast pick up things like distant waves breaking.
However, come out of some warm sector fog, and the visibility can be the absolute best. Sometimes it may simply lift into low cloud, and suddenly the rocks off the LiIzard point can be seen, so clear is the air. When I lived at Sennen visibility could flip to & from from being able to see Scilly really clearly (certainly 40mile visibilty), to a few hundred yards. It always amazes me that there is often so little of a transition zone. (Any excuse to show this!)
I did reply direct to Nick, but my post was deleted, I've no idea why. I can only assume it was down to an example I gave, which I therefore won't repeat, but I was disappointed. I though it a good example.