Watermelon is a fairly recent visitor to British shores, I think, unless we just never had it in the house when I was a kid.
When I first tried it, I found it a little tasteless, compared to the Honeydew or Canary melon I was used to. I prefer Watermelon now, the other stuff is too sweet.
I wouldn't dream of salting it, however. JSngry talks about adding sugar to berries - we used to do that with strawberries all the time in my choldhood. Seems a bit vulgar now