If your sprouts spoil, toss them out and start again. Give your sprouts a sniff. Healthy sprouts will smell fresh. It's a good idea to watch over your sprouts as you go and learn how they look and smell during this process, so it becomes familiar to you.
If your sprouts smell funky, not fresh or they if appear slimy, or if you notice a white or off coloured fluffy bits amongst them please throw them out. They're probably spoiled.
See the Food Safety information at the bottom of the blog post for more details.