They are "Legit" hardware as far as from HIK - these are not knock offs. However, what they typically are is hacked region cameras - meaning they are purchased cheap in China and are china region, however the suplier then hacks the firmware to put multi language firmware on them. This will result you not being able to update the cameras firmware 99% of the time as it will default it back to china region firmware.
The above isn't a "bad" thing as long as you understand what you are getting yourself into. As HIK also will not warranty the product and in some cases you may get a language mismatch error with a western region NVR, etc.