I had to remove my Purple martin gourds two years after I put bees at my house. The bees are south of the house, the p martins were East of it.
I, too, never had a problem with the martins. When they are feeding their young, a fair number of food-bugs get dropped by the inept baby birds. By far the most common are dragonflies.
MYTH: Purple martins eat lots of mosquitoes. Not true, they go for larger bugs.
FACT: dragonflies eat lots of mosquitoes. Connect those dots, if you will.
I loved having purple martins because they are unique in preferring to be near people, fill the mornings with song, and are beautiful flyers. It was a privilege to have them come every year. After I took down my pole, in spring, I had two sad weeks where the returning male birds flew around my house in circles looking for the house they used to use, and giving their distress cry. I'd had them long enough that most of my birds were born there.
If you enjoy shooting birds, shoot starlings and English sparrows. They are not protected, there are no seasons, no bag limits, and there is no end to them.
"Before I speak, I have something I'd like to say. . . . I will try to keep this short as long as I can." Yogi Berra