Does it even matter what the context of the open mic is much beyond a certain point or even the type of open mic? Are people going to complain about hearing a spicy email between singer-songwriter guitarists or between edgey standup sets?? No, it is guranteed quality content no matter what you are really just the messenger except you still get the experience of performing in front of people. Win-win for would-be artists and performers! Just keep it the right length, read the room and all.