I assume your spam filter is able to make the determination. :P Unless I'm not getting it, then do you have a specific example in mind?
Advertising/Spamming - Any form of advertising or soliciting members or commercial website linking whether publicly posted (including signatures) or sent privately (including email or PM) is strictly prohibited. This also includes, but is not limited to advertising with the intent to 'help people', or to provide 'free' products or links containing a referral or affiliate ID. Additionally, owners and/or affiliates of commercial websites who profit from selling (device) related products and services are prohibited from registering usernames resembling a URL of their site.