It's a complicated question...I REALLY hate digging harmonica parts. They sound really good and are usually deep. You (at least) think you got a nice button. It's complicated though because when I'm at a new site and it's the first thing I dig I'm happy to see them because they date the area as being 1800s....but other than that I HATE THOSE BUGGERS!!!
What do you hate to see in a hole (other than the normal bottle caps and cans)?
P.S. rifle cartridges are in the same boat!