In the last few decades, Scarlatti researchers have been providing some pretty compelling evidence that more than a few of his sonatas appear to have been written specifically for the piano in order to take advantage of the possibilities that the new instrument provided. Now the models Scarlatti had available didn't have damper pedals, and when they did show up the effect produced was not the same as what happens today due to marked differences in construction materials, sustaining power etc. That said, however, I don't see a problem with a very judicious use of the pedal to create particular effects here and there. (Obviously, you don't want to approach it like you would a Romantic or Impressionistic work). I expect that Scarlatti, being as innovative as he was and a pioneer of piano writing, would probably have jumped at the chance to explore pedal effects as well.