What is "authenticity"? Why is it a core value of blogging?
You can easily tell a spam comment from an authentic comment.
A spam comment is insincere, vague, irrelevant, or has an ulterior motive, an agenda that is either hostile or exploitive. They are using your blog comment field as an ad venue for dubious, malicious, or non-existing products. Spyware-attaching sites is where many spam comments link to.
Boiler plate comments posted hurriedly as part of an artificial, compensated, or company-mandated, these comments defending a product are always slightly off topic, or otherwise contrived. Using your blog as a message board, for free.
If you've been blogging a while, and using email, you should have great skill in detecting authenticity.
You also see authenticity and the lack thereof at work and in personal relations.
Authenticity means you do what you say. You stand by your word, even if guilty parties think you're "harsh", "abrupt", or "too direct". A chump is not authentic. He is a masochist with a "born to be victimized" mentality. They may issue a demand or command, but will not really check to see if it is complied with.
Chumps, wimps, pussies: all inauthentic.
Liars, con artists, exploiters and manipulators: inauthentic.
People who know how to "play" the system, the boss, charities, churches, and chumps: inauthentic.