I pirate games that are either not copyrighted in the United States, are no longer being produced in the United States, are no longer being profited upon by the original developers, or are only available for digital download from some service that I don't want to use.
The exception was that time I pirated The Sims 2 back in 2007 because my brother broke my discs and I wanted to play it. However I did pirate Fable: The Lost Chapters, Recettear: An Item Shops Tale, Princess Maker 2, Fallout and both countless Japanese visual novels/eroge and countless NES, SNES, GBA and Sega Genesis ROMs.
I believe that data is a form of information and that information should be free. Combine that with my old-fashioned desire for having a hard copy and outside of the stuff I pirate and various freeware I only pay for games that are currently being sold as a hard copy or have an incredibly affordable used hard copy available.
I believe the last used games I bought were Knights in the Nightmare, Brain Age and Capitalism II. The last new games I bought were Harvest Moon: A Tale of Two Towns and the complete collection of Baldur's Gate. This was back when I had the money to do such a thing, before I realized that in order to deal with this stressful environment I live in I had to spend my money on comfort food and stimulants. Even with what I said I pirate I mostly do it now because I don't have the money to go out and buy nice things at this time.
Oh well. I might be able to buy nice things again sometime soon. Then perhaps I can refrain from piracy for a while and not pirate games and such. Then again the only games I really want to buy right now I would require a modern PC or a XBOX 360 to play. How I long for Oblivion, Skyrim, Fable II, Fable III, The Sims 3, Record of Agarest War, Deathsmiles and BlazBlue. They genuinely sound like fun to me. For the time being though I am content with both pirating games I can play and playing games I already have, with Morrowind being at the top of my list.
I bought the Game of the Year Edition out of curiousity in my late teens simply because a magazine had said that there was a nude patch. I am most certainly glad I did not pirate that game outside of a NoCD patch for thousands of reasons more than just the eye candy that lured me in. But I digress for now I am ranting and thus should probably sleep or perhaps play Morrowind. Thank you for a lovely chance for me to express myself and rave about my opinions and paradigm.
TL;DR - I find piracy to be acceptable in some cases more than others, namely when it's something not readily available in your locale and/or you're dirt poor.