Man, you never had such a non-reaction to this work than at this moment. You were in such a neutral state, you didn't even feel like shrugging it off. Even a "meh" or "why?" would be more of a reaction than this warrants. It doesn't even tick you off over it, as would some cases of So Okay It's Average. The rule of thumb is that if you can't remember how you felt about that moment, it's because you didn't really have a feeling of it either way. Hence you have this trope.