Yahoo Site Explorer - Results not Accurate?

Yahoo Site Explorer has been very reputable in checking backlinks. A lot of webmaster and SEO's believe that it is far better that using Google search in checking backlinks. But recently this tool has given me doubts. I am launching Angelic Directory - the Human Edited SEO Friendly Directory, a new web directory soon and I have already started building its links. Being highly reputable in checking backlinks, I used Yahoo Site Explorer to check how my site was doing in obtaining backlinks. To my surprise the backlink results includes the text advertisement I placed in my signature in Digital Point Forums. This was not a live link at all and it should clearly not be included in the inlinks result. See this:

Click here for Inlinks Results for Angelic Directory.com

So with this discovery, is it safe to conclude that Yahoo Site Explorer is not accurate?