Guestbook spamming
Guestbook spamming : People are acting like it’s the greatest thing to hit Black Hat SEO since doorway pages ( hitwhores ) . So if a search engine sees too many generic links of this nature they can easily ban your site or penalize it.
Everyone knows a link from a .gov and .edu TLD is MUCH more valuable than our petty white hat sites. At least this way you only have to spam 10-15 reputable sites instead of spamming hundreds to thousands of not as reputable sites.
Source : http://www.bluehatseo.com
