My 2 cents on this.
In this particular case, if they guy has responded to a wanted add, as Adam is saying, I would just see this as information being passed on about a car for sale.
If I saw a post on another forum about the wagon I've got for sale currently, I wouldn't be upset. (I suspect they guys reaction would have more possitive if replys about the ute were more possitive. )

If however, someone drove past while I had the shed open (corner block so it opens onto the street) and posted my suburb and pictures of my shed contents up, I'd be less than thrilled. But this is just me being cautious from prviously living in a suburb (I use the term loosely) were hidden and bolted down was the only way things don't go walkies