But that's still counter-productive. To toxicity of the red wigglers will make them not want to eat, rather than entice them to eat. If they taste the red wiggler, they will associate that with the pinky, and decide not to eat it ever again.

It's like with humans: if you eat something that makes you feel sick, you tend not to want to eat whatever it is for a long time afterward. The same with red wigglers: it might entice them to eat once, but will also make them not want to eat it ever again.