The swing arm hydrometers are garbage IMO. I have had several and none gave an accurate SG reading. Also, salinity monitors (e.g. pinpoint) will also drift over time and can fail. Refractometers are probably the best & easiest, but also require regular calibration and checking against a stable source. Just calibrating to 0 SG really isn't enough. I use a floating bulb hydrometer to check my refractometer after calibration.

I was in CB a few weeks back and Mark was checking SG for a customer. He calibrated both his & customers refractometer and they were .002 apart. Then we pulled out a floating bulb hydro off the shelf, and got yet a third reading. Which one do you trust?

IMO, the floating bulb is the only true tusted source, but you need to make sure the water sample is within the temp band on the hydro, and used in calm water - I put a sample in a graduated cylinder for my floating bulb hydro check & compare to the refractometer after I calibrate. I do this about once a month.