Honestly?

The only way you can tell the difference is inside the self. The art can never be certain as contrarian or authentic dada.

Things like performance art, or the philosophy itself, the only thing that determines authenticity is the intent of the individual, and you can't tell that from the outside with complete authority. You can't even exclude what seems like contrarian expression because there's a degree of that inherent to dada. While the point of dada isn't to be contrary, you kinda have to be contrary sometimes in order to reject old paradigms via the absurd.