If I get myself into an area, where there aren't a whole lot of signals, I'll pretty much dig every beep, just out of curiousity (desperation). If it's real trash, I'll get real picky, and stick with signals that sound like something good. I'll be digging enough trash anyway. I discriminate iron, it's just too common, not worth a whole lot, and the rusty stuff can still slip through, will be digging some anyway. I'll dig a lot of the jumpy signals, that repeat. Usually junk, but not the usual trash, sometimes interesting, maybe something valuable someday. Most of my strange sounding signals, are keys (house, car, locks...). Mostly hunt curb strips.