Spoiler

A is a description of an  in a television show,  or book which if previously known may

Appearance
Once you it you cannot.

It either looks like or  Actually, forget the second part of that analogy, it's  that makes you think you won't enjoy the content anymore when it turns out to be you who made it unenjoyable.

Information
Spoilers are like superstitions, we're brought up believing in them without any rational explanation.

And there can't be a scientific study performed to prove whether or not spoilers do or do not make you find the material less enjoyable because of a number if things. How do we even know if spoilers actually ruin an experience for us? It's not like we can look at a spoiler, and not look at it simultaneously then experiencing the content afterwards so we can compare the two results, right? We'd need to erase the person's memory, have an exact clone of them, or do the same experiment with the same test subject but from an alternate universe.

Experimenting on spoilers would be like the Schrodinger's Cat concept.