To answer the question directly, I would much prefer having someone watch through a clear glass. Beyond that, I would prefer to have a female observer/s in the room. And the ultimate fantasy, is that I would like to be a slave practice dummy where the Mistress is training multiple Domme trainees who may participate in whatever activity is being taught. I would have no say in any of the activities. Come to think of it, maybe an audience behind a glass partition, where the Mistress is lecturing/demonstrating various torture techniques.