[RANT]
First you need a definition of a rock album. Everyone/every website has a different definition. I've been listening to hard rock/metal/heavy metal/rock for a very long time and I hate how today people are saying this and that is rock or metal or nu metal, etc. I also hate how a website will list U2 as hard rock.
I really wish there was a universal standard so that people would understand what everyone means by metal, hard rock, heavy metal, etc.
[/RANT]
That said, there are very few CD's that only have good tracks and that's certainly based on the listener. The albums I've been listening to a lot lately are:
Slipknot - Subliminal Verses 3
Spinshank - Self Destructive Pattern
Stone Sour - Stone Sour
Seether - Disclaimer
Sinch - Clearing the channel
For my tastes those albums have 90% good tracks.