I have a WD Black 1TB that's from when they very first intro'd the 1TB Black (5-6 years ago?) When the drive first spins up it sounds for sure like the end of the world is coming in death by nails on chalkboard. However it's been doing that forever and still works perfectly. Use a SmartMon program and it should be able to tell you when the drive is going to fail by.
Yeah, I don't know about some of these earlier Black drives. I also have a 1TB Black which is a little under 4 years old. It has gradually become louder as time goes on, and is now doing hard sustained seeks. After doing some benchmark tests and finding performance to be well below my low-rpm Green drives, I pulled it, and it's going to be RMA'd. Nice to have the 5 year warranty, but would've rather not had to use it.