I don't think that porn is necessarily bad for a couple. It depends on the individuals in the relationship.

When I was married to my husband he looked at porn and chose pleasing himself alone over sex with me. That was upsetting to me and I was not getting my needs met.

But in my next relationship my BF and I looked at porn movies and magazines together and he would say I would like to do that to you and I said do it. We both were pretty frisky and like to try variations and we even made our own porn film together (just for our own viewing).