I don't know if this is a coincidence or not but thought I would chime in....we pressure washed our deck, in prep for staining. Carried it down to the patio...one thing leads to another, hubby decides to PW the sidewalk....the following winter the sidewalk begins to deteriorate. It was almost like the sidewalk had developed a protective "patina" and when it was removed and not "sealed" somehow...the winter/salt caused it to flake. Looks terrible, but we can't afford new.
If you do pressure wash it, is it recommended that it gets sealed with something? (A little late to ask that question, I know....LOL) but I thought if it's a pool deck, various pool chems or a SWG pool? I don't know if any of that would make a difference.
I saw some beautiful stained concrete the other day while walking in the 'hood.