Comment Spam

How do people spam the comment box of blogs?

There is some jerk who leaves comments in some stupid idiotic characters which he himself may understand.

He has forced me to moderate comments -- What Moron!

My question is: is it really a person, if so, is he an idiot doing this when he does not get published? Jerk oK, but idiot, too?

Or is it a machine, if so, can google not do something about it like filtering the moronic source?

Well, we all come across morons in our daily lives -- sighs!