I live in land a bit but several of my larger jobs are near the sea. Our main problem is seagull mess in land as well as at the coast. Salt is much easier to clean off with hot as it dissolves much easier. Most of my coastal cleans are low frequency cleans so it was one of my main reasons for getting a hot system fitted.
Just as a experiment get a hot glass of water and put a teaspoon of salt in and do the same with a glass of cold water. You'll see what I mean instantly
As I have said before most of my work is commercial and low frequency so hot for me has saved me a lot of time and money. One job we do used to take 3 men 8 hours to do the outside, now two men complete it just under 8 hours. So for me there is now doubt its effective.