Re: "this application wants access to your microphone"
Why? Just deny it that permission and use it for the purpose you want to use it for, and not the purpose they want to use you for.
Their problem was trying to do this on the sly, instead of being upfront and compensating people for using them in this way. I'm sure plenty of people would be willing to do it if they were clear about what it would and would not do, and were getting something for it.