Why is 保证 in 价格还可以，就是不知道质量有没有保证?

Question

Among the (artificial) dialogues in the HSK4上 book (page 53) is:

价格还可以，就是不知道质量有没有保证。

I translate this to

The price is okay, it's just that I don't know if the quality is guaranteed.

I don't understand why 保证 is used here. It seems like it could just be 质量好不好 instead. It's possible that 保证 was added simply because the author was required to use the word 保证, not because it's normal to do so. The seller does not go on to offer a "guarantee", but just gives assurances of the quality.

But I'm not sure, as the usage might be different to what I'm accustomed to "guarantee" meaning (this book does that a lot---uses grammar and meanings that don't have English parallels).

Question: Why is 保证 in 价格还可以，就是不知道质量有没有保证?

I found this online which uses similar language, and one of the responses talks about 质保期30天, i.e., a 30-day "guarantee period". It talks about a literal guarantee, not just honey words.

Answer 1

价格还可以，就是不知道质量有没有保证。

I think 质量有没有保证 in the context checks on two aspects:

1. quality. (whether the quality is good or not)
2. guarantee. (E.g. one-year, two-year, etc.)

It would probably be clearer to write: 价格还可以，就是不知道质量怎么样，有没有质保。

Answer 2

价格还可以 - the price is acceptable

就是不知道 - just don't know

质量有没有保证 - can the quality be guaranteed or not

With 质量好不好, you are questioning the quality of the product being high or low

With 质量有没有保证 you are questioning the trustworthiness of the product's quality and also the trustworthiness of the source. e.g. "The quality of rice-cooker made in Japan can usually be guaranteed (质量有保证)- I would pay twice the price for a rice-cooker made in Japan instead of buying a cheaper American one(质量没保证) I just don't trust the American made rice-cooker since most of them don't even eat rice

Basically low quality product is usually untrustworthy, and untrustworthy product is usually of low quality.

A written guaranteed is called "warranty" (保证 or 保养 in Cantonese) , but it is a warranty on the product itself , it doesn't guarantee the quality of the product is high, just guarantees it would be replaced or repaired if it broke

Other example of product's quality can be guaranteed (质量有保证/ 质量信得過):

German car

Swiss chocolate

Jingdezhen Ceramics (景德镇陶瓷)

Quanjude Beijing roast duck (全聚德北京烤鸭)