Was transiting through the Iceland airport once and had a random thought about how I was quite far from anyone I know there. No sooner do I finish the thought I look about 20m in front of me and an old university classmate of mine is walking towards me.
Part of it is just getting a feel for Chinese goods and using that to determine what is a good deal or what is a scam. I’ve worked with a lot of Chinese suppliers for a long time so I have a sixth sense for their bullshit.
Generally I avoid anything that could be a safety risk (e.g. Mains power) , and keep an eye on the photos to see if they look too good to be true. Official stores are good, as are items with many purchases and reviews that include pictures.