It's the most idiotic type of spam.
And it's cluttering up the internet with garbage.
Recently this blog got hit by a bot (which means that the blog is on the rise and becoming more noticeable). Look at the first comment here and you'll see a vague response. Usually these types of responses are also filled with grammatical and spelling errors. Most publishing platforms (like word-press and even blogger) have filters that automatically take out the links or delete the comments outright.
But, some people still insist they have their uses. The only use I've ever seen for automated responses is as an indicator of incompetence. Any blog that publishes auto-response messages are either too stupid to see the exploit for what it is or too desperate for comments to care.
But the internet is being clogged with these stupid comments and messages with the sole purpose of generating quick and free advertising. If you want solid credibility, stay the hell away from spambots and auto-response scripts. Why? Because anyone who has a clue about blogging, publishing or the net can recognise them for what they are.
And the next thought your readers will have will be about your credibility.
Is this what you want them to be thinking about while reading your material?
Once again, I'm the exception to this rule because I've only allowed the publication of one to use as an example for this post. I'm well aware of the irony here.