there is no such thing as unintentional spam.
Of course there is. If someone is not aware of what constitutes spam and they write their post unaware of what that is, then it's unintentional spam.
example please
How about professional opinion: people definitely unintentionally spam from time to time. Often times it's when they're new here and aren't aware that they can't just blurt out random comments whenever they wish, but I vaguely remember some established members accidentally spamming at some point in the past.