We used to have this open mic showcase every thursday in my city and it actually got pretty big until the people running it got money hungry and started raising the price to perform. Those small pay to play shows are great but there more for networking and building your stage presence. The whole club would be packed but it would be 70% artists 30% fans so being that it was every week we started to see the same faces/hear the same songs over and over which isn't always bad cause one time I had this girl come up to me in the mall and she knew all the words to the song I performed the most. If you mean the bigger shows where you pay to open for bigger artists, I've done that once. I opened for Riff Raff but the thing about that is your music has to be similar to the bigger artists performing. My music was really trapped out and didn't catch on with a lot of his fans. You gotta perform something appropriate for that crowd