Mike from MI \"Iron Brigade\" said:
Next if you stop and think about it, the finds would be minimal. When someone dies a handful of people go to the grave side service and they stand there for a bit then leave. After that just a few folks visit the grave once in a while.
Mike, your logic makes sense only in modern terms. You're right about most cemeteries nowadays, there is not that much traffic by the grave site after the deceased is buried.
However, this was not the case many years ago. In the days before the internet, cell phones, TV, radio, movies, etc, entertainment choices were a lot more limited. In the early part of the 20th century and before, it was quite common for entire families to bring a picnic lunch and make a day of it at the cemetery.
I know many will disagree, but cemetery detecting does not bother me from a moral or ethical standpoint because I don't feel you are disrespecting the dead. The items you are looking for were dropped by the living.
That being said, personally I DO NOT AND WILL NEVER detect cemeteries simply because it is so frowned upon by the public at large. You look like a grave robber to many who observe you. A person who detects cemeteries is giving the hobby a black eye as surely as someone who leaves divots in a park. Also, in most cases, a cemetery plot of land is purchased and is private property.
I realize this is the Christian forum, but I imagine many of us would be thinking less than Christian thoughts if we came upon someone detecting at our family plot.