What does "yellow face wife" (黄脸婆) mean?

All the answer mean 黄脸婆 yellow face wife. Normally would say it to Woman only.

• 黃臉婆 （Traditional chinese， which is writing in Taiwan)
• 黄脸婆（Simplified chinese， which is writing in China)

Poker face is

1. 撲克臉（Traditional chinese), 扑克脸
2. 面無表情

As for traditional and simplified chinese, and why there look similar yet different. Please search relevant info.

古代女性所用的化妆品落后，一般所用的搽脸粉含铅，有毒性，长期使用会导致脸色变黄。所以年纪愈大的女性，受害时间愈长，受害愈深。故年长一些的女性就会呈现“黄脸婆”的症状。
_{黄脸婆 [huáng liǎn pó]}

The ancient women's cosmetics are backwards, with face powder containing lead, and those generally used are toxic, long-term use can lead to pale yellowness. So in older women, the longer the time of injury, the more severe. The older women will show a 'Huanglian Po'. 现代的“黄脸婆”

①大龄女人卵巢功能减退，导致内分泌失调，在皮肤上形成黄褐斑，脸色泛黄。

②指女子因各种原因导致肌肤表面老化，黄黑色素的生成，细胞沉积。

③指男人对妻子的贬称，往往感情出了问题，男方厌倦女方，婚姻出现危机。

④指容貌不好看的女子，不一定是中年女子，带有贬义，一般是骂人时用的。
_{成为黄脸婆的坏习惯，你中招了吗？}

Modern 'wives':

1. Older woman have ovarian dysfunction, leading to endocrine disorders, melasma forming on the skin, pale yellow.

2. Refers to women and is caused by aging of the skin surface, generating yellow melanin, cell deposition.

3. The mean man disparages his wife, often causing emotional problems; the man is tired of the woman, leading to a marriage crisis.

4. The appearance of women is not good, not necessarily for middle-aged woman, carrying negativity, is generally used.