"She thinks the quality of that store's clothes is not good."

Translation: 她觉得那家商店的衣服质量不好。

[RoryMichaelis]

What about ending in 不好质量？

[Dave168907]

In my way of thinking, there should be another 的 between "clothes" and "quality". Why not?

[Kivolamuzikisto]

There's another thread where this was explained very well, but basically it's because after you use 的 the 1st time (for store's) it's left out for the rest of the sentence.