The term spamming is misused a great deal, including here. When someone makes an inappropiate commercial post, it is not
spamming. It's inappropriate advertising, plugging, but it is not spamming. By the very origins of the term, an essential component is the bulk part. Posting an ad in a forum does just not qualify as spam. It may be just as undesirable, but spam it isn't.
There's a definition of it on Spam Canners at http://members.tripod.com/~SpamCanners/directory.htm
Its origins are included, as well as a sound clip taken from its origins (a Monty Python sketch).