Google’s Matt Cutts in one of his latest “Webmaster Help” video, answered a user question: " Should I correct the grammar on comments to my WordPress blog? Should I not approve comments with poor grammar? Will approving comments with grammar issues affect my page’s quality rating?"
A lot of people have probably wondered, particularly since Google launched the Panda update in 2011: how do the comments on your blog affect how Google sees the quality of your pages?
Here is the answer from Matt Cutts: