Personally, I pish, but as with all things, in moderation. It can be rewarding, as it was this past weekend on a walk down to Skipper Bay. The short section of trail I enjoy has changed character drastically over the summer: irrigation water has dried up, reeds have skyrocketed, and most of the waterfowl have moved on. There are still quite a number of black-capped chickadees about, as well as a few hardy mallards and great flocks of European starlings, but other birds appear only haphazardly. If not for my pishing, the best bird I saw might not have appeared at all.
Walking along the beginning part of the trail just a few dozen yards from where I'd parked, I heard rustling and a buzzy "chuk" call from the reeds to the east. Watching carefully, I saw a bit of flitting accompanied by tail flicking, and knew there was a wren hopping about. But which wren? After just a pish or two, the curious bird poked out of the reeds to watch me as intently as I was watching it, and a few minutes of pishing later, the beautiful marsh wren came into full view. It was a delight to interact with such an inquisitive and responsive bird, and that is why many birders do enjoy the occasional pish.
This time of year, when juveniles are maturing and birds are prepping for their long flights or frigid winters, a moderate amount of pishing does no harm. I try to avoid pishing in the spring and early summer, however, when young birds might be left defenseless as parents respond to the threat my calls may sound like. And while this wren may have been simply curious and willing to play, many birds wish birders would just mind their own pishness.