It's not just GC. All music stores, even online ones, do not accept returns on mics and headphones. Basically once you walk out the door it is considered used unless it is wrapped in cellophane.
There isn't any health issues. It's all about $money$.
They all figure that they know you aren't happy with the microphone and don't want it, why not offer you a cheap price for it then jack the price back up for resale! Even though you only tested it over night. I used to be able to do that all of the time.
But now they don't have a problem with you checking out a microphone in the store before a purchase isn't that just the same so called Health risk BS? It goes right back for sale
Those .... Microphone Onsite Threat Handling Environmental Recovery and Fumigation Under Close Kinetic Energy Restraints Services!!!!!