Are you talking about ads with no price, just "make an offer"? Or ads with an OBO included in the price?
Most anything I ever sell has a little wiggle room in it. So I can see adding OBO to an ad to welcome those that think you're asking too much. I can also see a person having something they don't know the worth of taking offers to gauge what it's worth. If you were a woman that got your ex husbands guns in the divorce, you might sell them this way. So I have no problem with either method. I'll offer what I offer, and that's it. The seller can take it or leave it.
I also tell the person making the offer if I've had a higher offer than that already to give them the chance to reconsider.
Most anything I ever sell has a little wiggle room in it. So I can see adding OBO to an ad to welcome those that think you're asking too much. I can also see a person having something they don't know the worth of taking offers to gauge what it's worth. If you were a woman that got your ex husbands guns in the divorce, you might sell them this way. So I have no problem with either method. I'll offer what I offer, and that's it. The seller can take it or leave it.
I also tell the person making the offer if I've had a higher offer than that already to give them the chance to reconsider.
