The smell is probably not good, but I would go ahead and plant all of them. I have had some seedlings with a red leaf or red splotch before. I don't think it is the deadly amaryllis virus, but some other problem. When this happens, I remove and destroy the red/splotched leaf, and the rest of the leaves usually are fine and stay green. If you only have one leaf and it is red, I would leave it and wait for the next leaf to grow, then remove the red one. I'm not sure if it is an actual disease, or just a sign of distress, but I do seem to get them if I water too much. Hope this helps, and good luck on your babies - keep us posted!