I find that pins corrode, esp. if the pincushion is made of the "wrong" stuff. I made one with crushed walnut shells and it ruined my pins....had the throw all the ones in that cushion away. The wool one, or even plain stuffing are good, and any that get a little dull, I push through an emery pincushion a few times. I ordered the emery...somewhere....can't recall now.
I love the Clover pins, too. A few years ago I got some that were great, sharp and smooth, they came in a little box, glass tops blue on one side, yellow on the other. I few months ago I ordered what I thought were the same, well they LOOK the same, but they are much thinner and bend easily. Unfortunately I threw the package away, so I don't know if they were produced to be thinner, or they are just made cheaper now, as many things are. The new ones are usable, and great for fine materials, but I do have to be careful when pinning quilt blocks with them.