What makes you trust a certain supplier that you haven't ordered yet from? (Alibaba)
The fact that I order a sample from a supplier and I'm pleased with the quality isn't an indicator that this is a good supplier. A Big part is whether he can maintain the quality throughout providing a larger number of units, i.e 50+.
How do you handle the sourcing process when it comes to such trust issues - or rather what backup plan do you have in case things go wrong, because it's less a matter of trust but rather what legal backup do I have. I've heard multiple stories about Alibaba not wanting to refund buyers in obvious cases - even when someone had Alibaba Protection or Trade Assurance. I've heard stories about that too, that it doesn't give or do much - even when I entered this subreddit right now - already top posts are some scam stories, and also the fact there's a bunch of trade companies with huge markups not actual manufacturers on Alibaba..
Also - products can be faulty in various ways. It can be a small flaw but a one that has a huge impact on client's experience which will also result in bad reviews and it's considered unsellable stock from a business owner perspective - but maybe considered as "not big enough flaw" from a manfucaturer/Alibaba's perspective to accept return.
Product may even look the same, but be made from different kind of material than the samples I've received, or have different texture - that's hard to prove over just photos. There are 100 scenarios in my head, and logically I can see Alibaba not being keen on any refunds for most of them. Especially when the products are custom i.e with your logo - if you return it to the supplier he can't resell it, it's 100% loss for them, hence I imagine accepting returns must be hard.
Oh - and when it comes to ordering some kind of quality checks from chinese companies before the products are shipped - I was thinking about that too, but with new suppliers I order rather small batches at first of around 50 to 100 units per 1 product, so it doesn't pay off. It pays off with larger volumes like 500+, but if I order 50 it's too big of a cost. Nonetheless it's a good solution to monitor quality once the the volume is bigger.