Its a sad moment when you first have to explain to your mother/client/etc that no, Discount Oakley Sunglasses didn't really enjoy your superb post. Its a shockingly effective spam tactic. People cannot resist praise.
Why does it matter if Discount Oakley Sunglasses really enjoyed your post or not? As long as the writer feels more motivated to continue writing afterwards, then what do you possibly achieve by telling him or her that "oh, don't believe in that compliment, it's CG'd". Yes, I agree with you that it is a sad moment when you have to break through people's ignorance make them see the ugly side of the world, but it's sad…
If there is a worse thing than a blog with no comments, it's a blog with only spam comments.
They're the cobwebs of the internet.