As an allegory, what is implied by 《三打白骨精》
I don't believe there's any special implication. I bet it's just a fun story to watch, as it involves a beautiful female demon(妖精) trying to eat the monk(唐僧)'s meat to achieve immortality. 

However, 白骨精 does have a modern interpretation which is short for 白领 + 骨干 + 精英, which is not related to this, but does (usually) refer to beautiful women, who are white collar elite worker, with high level education and income. Refer to definition here: Baidu