Most are one shot. Cheap and disposable. Better to toss them than decon them. When I first got in the field the opposite was true, but when you think of it , would you really trust that they were clean after a really bloody use.
There is a company that makes an excellent shear for EMS but they are between 100 and 200 dollars US.So I just use the cheapos.
Many can be reused with a little TLC.Any are fine with light use ,just the heavy stuff that dulls the edges and loosens the rivet.
Just My opinion.