Never been part of an orgy myself, but have had a few threesomes and for the most part enjoyed them.
My reasoning for liking to watch orgy porn may seem different to some. I like the scenes where it's mostly male dominated. Some might look at it and think the woman is being degraded, but I see the women as powerful. They're the center of attention and somehow get all the men off. With scenes that are mostly women, it seems like the gals do a better job getting each other off.
Maybe I'd like to participate in one someday, but it would really depend on the group of people involved.