i've bought 2x 5600, 1x 7500f and 3x AM4 motherboards in the last year and a bit
no issues with all of them so far *touch wood*
it's a 20-30% discount off official routes, and as always, you pays your moneys and you takes your chances
(no different to buying used, second hand parts off ebay/gumtree/FB, really...except these chinese parts are more likely to be new)
A Chinese motherboard on a local network. Danger, Will Robinson.