not always,... why..?? some member of forum just rad the thread not visited your sig,... that is the fact
I think forum posting will always be a controversial topic with regards to getting traffic from them. I think that although many people devalue a forum with stupid or spammy comments there are some people who really contribute valuable information. Those are the people who motivate me to click on their link. So in order for your time at a forum to be worth while with regards to both SERPs increase and Traffic increase you MUST contribute quality information. This is just another proof that quality always outweighs quantity.
i think it depend i got more result for my adult site when post at adult forum ,it all depend on your niche and where u post