@华金，

Great explanation for 阴魂不散. It can be used as a metaphor to describe old problems or bad systems or thoughts just don't go away easily.

i.e.在非洲，奴隶制度仍旧阴魂不散。

As for 百足之虫，死而不僵. It's commonly used as a negative expression - People or Groups who used to have money or power have been taken down, but their influence and prestige still stand for a long time.

比喻某人或集团虽然失势了，但仍存在一定的气势和能量。