Piracy is bad, pure and simple. It's stealing, with that being said in my younger days I often did it so I could test games. If I liked the game I bought it if I didn't like it I didn't buy it.

However with this being said, I think Piracy and Emulation are two different things. Pirating a game that a studio can still make money off of, is as good as stealing. However, pirating or emulating a game from the early days of gaming, from a studio that is no longer around, or a game that is no longer making money, IMO is perfectly acceptable.

For instance, I would never pirate the newest Zelda game, but I would download an emulator to play, say, Ocarina of Time.