The concept is simple, they are "feeling out" trade or sale opportunities. However, in a normal classified listing, you are not required to accept any trade or cash offers, full price or otherwise. So the question is open, why do so many people write "feeler" on their listing? I just noticed one today that said he would put out a feeler because there were so many others. Then bumps it 8-9 times. Are these not simply normal ads? Why do people feel the need to describe them as "feelers". Mind boggled I guess!