Been a heavy (1k+ items) alibaba and aliexpress buyer for about a decade. I think I have only been scammed as in not receiving the item or receiving a different item a couple of times and never had an issue with ali returning my money from escrow.

To the issue of item quality I have a couple of takeaways. First, number of orders are listed for each item, I usually stick to items with at least a dozen + sales. There is a way to sort by number of orders. The second would be the is it to good to be true rule. You can definitely get good, sometime amazing deals on ali but for example, if on amazon you are seeing a 20,000 mah battery packs going for $50 on amazon and then you see it for $10 on aliexpress, good chance you will get a 5,000mah battery labeled as 20,000mah. For a 10$ pair of kicks, they'll show up but are likely going to be pretty low quality. Finally would be name brand goods, these are likely going to be either counterfit or greymarket (like where the legit factory just runs the production line a bit longer). Quality will vary greatly from trash to indistinguishable from the original.

One final thought is sellers are usually pretty accommodating in my experience because they are looking to win those bulk orders. Ask them for more details, pics, etc. For some things like clothes, they may have different qualities they can sell.