Lightroom's Dehaze tool can be a lifesaver in certain cases, bringing back photos that you might not have been able to recover otherwise. But that doesn't mean you should always use it whenever you see a bit of fog or haze in your photos. This great video shows you the ins and outs of the tool and discusses the best and worst cases for its usage.
Coming to you from Matt Kloskowski, this helpful video discusses how to best use the Dehaze tool in Lightroom as well as when it's best to leave an image alone. The Dehaze tool can really save an image sometimes, and I find it especially satisfying to use when I have an otherwise good image that seems frustratingly ruined by a bit of atmospheric haze. That being said, I think Kloskowski touches on an important point when he discusses leaving it in the image at times. When we have a tool at our disposal, it can be easy to fall into the habit of using it by default without thinking about if we're actually improving the photo or emphasizing what we want to in the image. As he discusses, sometimes, the haze is actually a benefit. Check out the video above for his full thoughts.
Painters use this 'haze-in-the-distance' effect deliberately. It's called aerial perspective and was first documented in the 15th century.
https://en.wikipedia.org/wiki/Aerial_perspective