I think that there must be something not quite right with the current system, or we wouldn't all be talking about changing it.
For those of you who do like to "happen" upon things, are you saying that you wouldn't actually look in the Frames and Forks section unless you were looking for a frame and fork? I suspect that you would look anyway! I know I would, I mean, I look in the For Sale section even though I don't need to buy anything!
Having said that, having multiple FS forums would not actually stop people having multiple threads at all either would it.
I think that this forum works because we all care about it, if we are not happy we say so, and if we are we say so. Can we not simply encourage people to advertise in a certain way through persuasion? PM someone and tell them that they should consider reducing the number of threads, or that you think they bump too much, or suggest they sell it on ebay if it is not selling here.....
Rather than having rules, if anyone on here is p***ing others off by the way they sell, let them know, or don't buy from them.