I passed my test first time around but when taxiing back from the final landing I was certain I had failed.
Among my errors were a serious inability to maintain altitude in an instrument turn, a seriously screwed up approach resulting in a go-around, a completely failed power-off landing and a (very) far from perfect engine failure after takeoff.
The examiner, however, said I did very well and was ready to overlook the errors he confirmed I had indeed done. The instrument flying wasn't easy because of turbulence, I had done the right thing by going around from my flunked approach and my EFATO didn't kill anyone. The only thing he was concerned about was the power-off landing but as I did it better on the second attempt and had done a successful PFL he saw no problems with passing me. He was also happy with the way I handled a runway change in the pattern as well as my general attitude and airmanship.
My point is simply that you shouldn't focus too much on any eventual mistakes you make. As long as it isn't dangerous and you take appropriate corrective action it's not going to be a problem. And if your general flying is good then the examiner might even be ready to overlook a more serious blunder if you get it right on try two. I thought I'd made one mistake too many to be passed and in the end he really only cared about one of them.
EDIT: And this was a checkride for CPL. Presumably, on the PPL ride, the examiner is generally more tolerant.