"And if it's in the blacklist, don't tell the user at all, and instead start introducing subtle errors everywhere. "What, you saved it yesterday and now it doesn't open? Whoops (snicker)." Or, misalign printing so anything looks good for a draft but not 'professional' use. Or you could go the obvious route of slapping a banner on it, but that is usually easily removable"
"Gee, I'm sure glad I decided to pirate [program], it's buggy as hell. Better warn my friends..."
Spyro: Year of the Dragon used a similar technique to great avail. Don't be so quick to dismiss this method of deterring crackers. It just needs to be done right. There are arguments going both ways on this issue so it's simply not black and white. Perhaps it works better for games than applications, but again, you'll find arguments going both ways for games and apps alike.
"Gee, I'm sure glad I decided to pirate [program], it's buggy as hell. Better warn my friends..."