I've never received a faulty one, but pushing 60psi through the house to the hose faucets makes these last about 2-3 years with daily use (on an automated timer) and are an absolute must unless you want sprinkler heads flying around the yard.
I don't see why you can't bury it under a couple inches of dirt, I put mine on the water timer which is mounted to the 3/4 PVC 60 PSI supply line, makes it easier to take down in the fall of the year.
https://www.digcorp.com/uploads/download/file_us/15/DripGuide_032117-Web.pdf Here is a link to the manual on the Dig website. I followed this diagram and my system worked really well.
Not sure if failure caused by contamination and unsure how to determine that.
I have had this problem, spending way to much for replacements. I use aluminum gutter screws with a little rubber glue on the threads. You only need to turn the threads in til they catch, then half of a quarter more. I have not noticed any problems with this fix. Pressure is still regulated.