Well I dont think your issue would come from classifieds in any way.
Very very explicitly we only call the inc post function when a user uploads an ad and a user places a comment.
now here is a portion of that code
Code:
Content visible to verified customers only.
I dont think an update mysql command to increase posts by 1 or decrease by 1 that is only called once during an ad upload or comment is going to increase posts any more than that.
So unless you have users a making billions of ad posts or comments its not going to happen. You also can turn off the ability to increase posts on the forum. I would suggest you do that and see it still climb thats gonna tell you its something else and also rule out classifieds.