I had an hour to spare and wanted to smell the delicious flux, but didn't have any project to work on, so I decided to take all my different solders and do a quick comparison with them. Basically, whenever I've bough something from ebay, I've added a spool of the cheapest solder currently sold, just to see if cheap could be good (spoiler: the answer is no). Also because I was really running out of my good solder, and the label was torn so I couldn't get more (I now know it is made by Solnet, and have found where to get more, so no more crap solder for me).
Anyhow, here are the spools in question.
All (at least sold as) either 60/40 or 63/37 leaded solder.
And here are the results; from left to right:
Kaisi, Kewei, Kaina, Bojie, Yong Chang, no label, and the good old Solnet.
At the right, side by side of Solnet and Yong Chang, both 0.8mm 60/40.
And from the other side:
My thought was to make a nice detailed comparison, but as the results are all horrible, I didn't bother.
They all smell terrible, take ages to heat, stay pasty for too long, spit burning hot flux everywhere, and if they aren't dull even when molten, they will dull the moment they solidify. So let this be more of a confirmation/warning than a review, cheap solder is cheap because it's crap.
Also, Solnet flux smells addictively good. Kaisi smells like burning cat urine.