~~~ to a switch plate/receptacle plate with a brush or the proper masking tape, there will always be the possibility of getting a speck of paint (which can be unnoticeable to the naked eye) on the edge or even under the plate and, should that plate ever need to be removed for repair or replacement (they do crack with tension/fluctuating temps).... there's a strong possibility that you'll be left with a huge chip of peeled off paint on the finished wall from that little speck that was left on the switch plate... and now there will be the job and valuable time spent in making the repair to the damaged, painted wall which could have been avoided if the switch plate was removed to start with.