I expect my experience with Ali Express is what many prospective customers worry about: Sales people are available over email when you want to buy something, but there is very little recourse when things go wrong.
My order was rejected. The only way to appeal was with a button that didn't work and the charge is still on my card. For how long, who knows. Not confidence inspiring.
Retail customers are very price sensitive (Unless they are of the iTard persuasion). Race to the bottom. So you have to expect level one customer service (Or zero in this case). But the order acceptance, then a possible 24 hour delay for confirmation, then an order rejection with no stated reason and no way to contact the vendor is frustrating.
Having used CCs all over the world for decades, I've been rejected by Visa/MC countless times. It's the principal reason for carrying Amex as a backup. But when the credit rejection is through Visa/MC, (a) It is instant and (b) You can call a number, verify your identity and the transaction proceeds. Not so with Ali Express in my experience. They are acting as a credit verification intermediary. Probably, as Nayr suggested, out of necessity. But the 24 hour delay is a pain when you are ordering other related items for a job and the failed appeal process obviously not good enough.
Okay, I've had my gripe for today (Enough for a month). Have to move on and look at other sources.