This section of the forum is for discussing trades, so they are organized and not mixed with other topics. Because there is a section dedicated for such things, I see no reason to lump all trade discussions together into the same thread. As long as the trades are new and not mulit-post or off-topic, there should be no confusion as being spam.
If anything, when someone starts a thread, anything other than a response to the thread-starter or previous post could be considered spam (in my opinion).
Perhaps we need clarification from a Community Manager....