The RF Transistors that are found in aliexpress may be fake or second hand so I say pay attention..
There are so many claims about them in the internet..
A second hand transistor (good not burned) would work the same as a brand new one. Transistors doesn't have an expiry date...
Otherwise, it is true. Some MOSFETs from China are fake or don't meet the datasheet performances.
But the good side of this trading (especially buying from Aliexpress site), if you receive a product which doesn't meet the specifications, you will get full refund...if you ask for it of course...