Don't ever think a question is silly if we can learn from the answers. Yes, ball point needles will and do become dull. They are made for knit fabrics so a hole isn't made piercing the fabric the needle moves between the weave of the fabric. I would not recommend using them for cotton fabric as they will make holes in the fabric because the tip has too round of a point, and the cotton fabrics have a tighter weave. Hope this helps?
Suzy