I am a little confused as to what is going on…
take this forum post as example: http://www.aquariumjunkiescanada.com/forum/forum-rules-and-information/how-to-get-your-own-webpage-on-aquariumjunkiescanada
if you look at the code for sharethis share on FB button, you see:
<span class="st_facebook_hcount" displaytext="Facebook" st_summary="At AJC we offer Free custom webpages for our active members. ABSOLUTELY FREE (Donations will be greatly appreciated) Photo galleries are controlled by you! pictures can be added, deleted or changed any time. Page layout is fully customizable and page Design/colors can be changes by request. Ads can..." st_title="How to get your own webpage on AquariumJunkiesCanada" st_url="http%3A%2F%2Fwww.aquariumjunkiescanada.com%2Fforum%2Fforum-rules-and-information%2Fhow-to-get-your-own-webpage-on-aquariumjunkiescanada%23p13" st_processed="yes">
<span class="stButton" style="text-decoration:none;color:#000000;display:inline-block;cursor:pointer;">
<span>
<span class="stMainServices st-facebook-counter" style="background-image: url("http://w.sharethis.com/images/facebook_counter.png");"> </span>
<span class="stArrow">
<span class="stButton_gradient stHBubble" style="display: inline-block;">
<span class="stBubble_hcount">9</span>
</span>
</span>
</span>
</span>
</span>
which looks right to me… the url, title and excerpt that FB is notified of appear all correct…
yet, when FB goes to share, its wrong…
I think what is going on is that you are also running jetpack for WordPress and you have turned on the OG tags stuff in jetpack… and it does them wrong for the forum page… so you end up with multiple open graphs tags – jetpack which is wrong and ours which is correct…. so FB gets confused…
so first question, are you really using the jetpack (which is horribly greedy btw) sharing functions elsewhere in your wp site? If not, you should disable that feature of jetpack… jetpack stupidly enables dozens of features and relies on you to disable the ones you dont want – good for slowing down sites…
if you do need the jetpack sharing elsewhere on site, then you will need to disable it (via jetpack hooks) on the forum page only so it doesn screw up facebook…