Could the Tantabus leaving Luna's dream good or bad?

[cider float 2,539]

The Tantabus is a very powerful and frightening thing alright. But what does it really do? I feel that since it was created by Luna to punish herself for her crimes, the Tantabus may have been some kind of regulator against wrongdoings.

 

Could this have been a good thing though? The Tantabus seems to be about stopping evil thoughts and that might be what it was going to do.

 

But would punish anyone that have some kind of malignant thought no matter how small as Luna used it to overly compensate for her faults. Like if Rarity felt like just slapping Blueblood in her head the Tantabus would have punish her gravely by giving her great pain. So it would have gone around punishing others for just thinking of doing something that was bad.

[cmarston1 5,964]

I am pretty sure that it was meant to be a good thing that the tantabus left her dreams.