Personally, I think we should vote down and comment, rather then editing in a disclaimer.
I think the editing approach just invites more of the same and isn't in the spirit of the rule, which includes the idea that posters just interested in promotion are here from the wrong reasons. Even if the edited post ends up being helpful in that particular situation, we don't get an engaged community member interested in making contributions beyond the promotion.
Allowing the posts but putting in our own disclaimer teaches people that we're a fine place to drop such posts.
Voting down and commenting gives an opportunity for someone who came to the site initially attracted by a question a need which their product is designed to fill to become a real, helpful member of the site.
If the post is really blatant, if it isn't improved, it should then be flagged as spam and deleted.