Forum:Fake Cards?

I like to visit this site for its realiable contents and help from other duelists. But something bothered me..some of the people here mentioned "sell this card for cash..", "cheap deck yet strong","you need to budget your needed cards first..."

Well I don't know if its bad or not to use fake cards NOT on real tourneys but on just ordinary duels. How do I know if its TCG or OCG? ex. I have a card named "Zombie Carrier", but after searching it here..i found out that it was Plaguespreader Zombie. Theres even a fake card of it..named "Corpse Carrier". It's called piracy right?