I was very, very nearly terminally discouraged by the "I'll pass you but I shouldn't" approach, after a minor test early in my training... From someone I later realised had a personal gripe. He also took it upon himself to assure me I would never make it through the next stages. I believed him and spent a wretched couple of months watching my flying, and of course my confidence, get worse and worse. I then did what I should have done as soon as I left that room, and went elsewhere. It took a while to get the confidence back, but I went on to pass all subsequent tests first time.
I have quite a few friends who teach, in one capacity or another. They have pointed out that comments such as "I'll pass you but I shouldn't" are not only poisonous, but completely unprofessional. You pass someone (with whatever dimension of debrief) or you don't. To do something in the middle is very effective psychological sabotage, and should never happen.