Sally on the WE(s)T Side
Pixey, my standard tests:
If the answer is yes to any of the above, then put it in an old medicine bottle with a child-proof lid to be disposed of properly. Otherwise you can use them. You can use some questionable needles to make paper fold lines in computer printed patterns (lengthen the stitch and don't use thread) and for decorating cards with stitched designs.
Sally, who has a pincushion full of machine needles
I have been getting my sewing room back in order and unearthed 3 different pincushions where I had stashed gently used needles. This was usually from where I had done a small project (not enough to wear out the needle) but the next project needed a different needle but I kept forgetting to go back to the slightly used one. Most of the needles are blue tip and purple tip, with a couple of red tips and Organ Topstitch needles thrown in as well.