The inspector left a message referring to 110.3 and mentioned that receptacles haven't been tested to be painted over? I don't see anything in that section that would prevent the painting of receptacles. And if UL hasn't taken on the issue of painted receptacles I don't see how that could be used as the reason to fail the job.
The only reasonable argument I can see is 110.12(B) Integrity of Electrical Equipment and Connections: 110.12 Mechanical Execution of Work: "Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces, shall not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, abrasives, or corrosive residues. There shall be no damaged parts that may adversely affect safe operation or mechanical strength of the equipment such as parts that are broken; bent; cut; or deteriorated by corrosion, chemical action, or overheating."
In this case, the painters in no way affected the internal parts of the receptacles or switches.
I'm getting ready to state my case to the inspector. Thanks for all of the input, I'll let you know the outcome.