Yes, seam rippers dull, just like scissors, knives, rotary blades, etc. :-( They are not all equal in the construction either. I like one that has a fine tip on it so you can slide it easily under the stitches. With that said, I usually slip it under and cut every 3-4 stitches along the seam and then pull the thread on the other side of the seam and wal-la the seam is out :thumbup: . You just need to do a little thread picking or use a strip of tape to get off the thread tales and you are ready to resew!