Really Stupid People Do Really Stupid Things
I have yet to meet a polis who understands that "fishing expeditions" are wrong.
When I was at university, "being a student" was justifiable grounds for being the target of illegal police surveillance. Producing the annual student concert earned the producer a file at one of the security organs.
Downloads, heavy metal, bikes, gangs - sounds like a good opportunity to flesh out the photo album, pick up some bail defaulters......... you get the drift.