Matt Cutts, Google’s head of webspam, wrote a post on his personal blog telling people to beware of comments appearing on blogs and different sites around the web claiming to be from him when they’re really not.

“A lot of the time, I dispel misconceptions by leaving comments on blogs,” he writes. “That works great, except for the rare occasion when someone pretends to be me and leaves a rude, fake, or otherwise untrue blog comment. Over the previous decade, I’ve only seen 4-5 times where someone impersonated me. But in the last month, I’ve seen at least three nasty comments written by ‘fake Matt Cutts’ impersonators.”

He points to a couple of recent examples, including one where the impostor said Google uses the credit card numbers of AdWords advertisers as a “strong signal” in organic search.

Cutts is telling people to verify the legitimacy of the comments made by people claiming to be him on Twitter, if they’re at all skeptical.

“The web isn’t built to prevent impersonation,” he says. “On many places around the web, anyone can leave a comment with someone else’s name. So if you see a comment that claims to be from me, but makes crazy claims (e.g. that we preference AdWords advertisers in our search results), let me know. I’m happy to verify whether I wrote a comment, e.g. with a tweet.”

He has indeed been doing some myth busting on Twitter today, including tweeting out a video addressing that classic about giving preference to advertisers:

“The answer is no,” he says in the video. “You don’t get any benefit in Google’s organic or editorial search rankings if you decide to buy AdWords. There’s no boosts. There’s nothing going on in the algorithm there, where if you buy AdWords, you will rank higher in Google’s organic search results. So don’t count on that.”

When someone asked Cutts on Twitter how they knew his tweet really came from him, he replied: “Because now you have a verified tweet. Please don’t make me do a video to verify the tweet.”