Yes, you take your chances - there's the occasional outright scam, or so-so quality parts (like the ones that inspired me to write this), but you go into it with your eyes open. You take a chance because it's dirt cheap.
And 90% of the time, the parts are just fine.
For anything important, or safety-related, or mains-connected, or anything I build for other than personal use, I won't use yum-cha parts like this. For those, I order good name-brand parts from a reputable supplier (Newark/Element14/RS, DigiKey, etc).
But for hobbyists just having fun, messing around? AliExpress and friends are an absolute godsend. You can now get into hobby electronics for practically nothing, and build stuff and see if you like it.
There's a place for quality parts, and a place for cheap parts. Knowing which is which isn't hard.
Three cheers for cheap components!
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