I have noticed an pandemic of spam on youtube, the more popular the channel the more spam. In some channels every post is "Earn Money from Home, click this link!"
But yeah as I said youtube put things in place to remove crap like that, put it was up to the channel owner to act. Someone smapping the crap out of the commnet section... you write their name in the "Don't allow posts" section and problem solved. But some channels are very large, so it would be hard for them to do so. They would need a full time person just removing the spam.
But hey there is an idea for Googletube. Just hire some people to be moderators. They already have people to make sure porm and such isn't being uploaded. Just get people who check for spam. Or better yet and I am sure it is possile. Write a program to remove spammers. Or have all of the above, channel control over posters, moderators and a program to remove spam.
No need to go nuclear.
Also thinking about what could be causing all the spam is Google's endless need to gather so much information on everyone. Spammers get all the info and they can create endless zombie accounts.