Science is very limited in it's measurability. Consider a thing like when children do something that's cute.
The first time they do it, it might be cute. Heck, even the second, third or fourth time it might be cute. It might be cute no matter how many times it happens. Depending on what it is, it might be incredibly cute the first time it happens, and incredibly annoying the second time. There's no way to use measurements to predict how particular people will respond.
The same can be said about love, hate, or any emotion. In most cases, you can't measure what will set them off, and what won't.
I think psychic abilities fall within the same categories. And I also count on human falliability. We're all human, and sometimes we're wrong.