I doubt the possibility of a justified expectation of the pleasantness of a surprise. Any situation where information is being intentionally withheld by a human creates a higher prior probability that the surprise is unpleasant for the simple reason that the majority of humans find sharing good news a pleasant act and something they are more likely to do than sharing bad news. Thus, even if the eventual outcome is pleasant the anticipation of a negative outcome reduces the total fun involved both prior to the reveal because of anxiety and after the reveal because of resentment, and it is entirely reasonable that an individual could find these negatives to reduce total Fun more than the pleasant surprise increases Fun over a baseline of the event itself.
I doubt the possibility of a justified expectation of the pleasantness of a surprise. Any situation where information is being intentionally withheld by a human creates a higher prior probability that the surprise is unpleasant for the simple reason that the majority of humans find sharing good news a pleasant act and something they are more likely to do than sharing bad news. Thus, even if the eventual outcome is pleasant the anticipation of a negative outcome reduces the total fun involved both prior to the reveal because of anxiety and after the reveal because of resentment, and it is entirely reasonable that an individual could find these negatives to reduce total Fun more than the pleasant surprise increases Fun over a baseline of the event itself.