Over the years the reputation of Metal Detecting Clubs has come under fire from both public and professionals alike. People see TH'er's out there that probably do not belong to a club or care to. These people sometimes don't "replace their divots" or care about cemeteries, national monuments, battlefields etc...
In the public's eye, these people are no better than common thieves and vandals. Stealing history and defacing property.
To Professionals (archaeologists) these people make their job tougher. They have to stay one step ahead of these "robbers". Once an announcement of an historical find hits the press, the night hawks come out and destroy any historical significance the site ever had.
This is why we must try to reach these people and either turn them around or point them out. We cannot let our hobby be ruined by a few bad apples. We must also teach new "Detectorists"the proper way to use a probe, dig a find and leave the area as good as new.