Couple of funny stories along these lines.
I knew a guy, Steve, that worked for me in the past and was kind of a prankster. He would do things like set up vine/twig doll (like from the Blair witch project) in front of a guys deer stand or put a buck skull on some brush down from another guys stand so that the antlers were above the brush and moving in the wind... This guys was a really skilled point hunter. He still had the most impressive collection of axes, points, etc. that I have seen outside of a museum. He would often hunt points with another guy that would walk past points. On one prearranged point hunt, Steve took a large point from his collection and wrote the other guys name on it and placed in a obvious part of a creek bed that they were going to hunt. So needless the say this guy actually found this point. He was so excited until Steve said "that's a great one! it looks like it has your name written all over it" then the other guy turned it over !
When I was in grad school I worked at a sanctuary in the Poconos. This property had only been owned by three families in the last 150 years (approximately 640 acres with a 56 acre lake). It was rather untouched. Back in the 40's they had a storm that had hurricane force winds come up through one of the valleys that knocked over hundreds of trees. They set up a mill on the property to mill those trees for lumber. In the mid 70's there was a archeological grad student that was looking for burial mounds on this property. He came upon a spot in the forest that appeared to have well over 40 mounds. He secured funding from the University to dig on some of the more prominent mounds. They spent the whole season mapping and digging several of the mounds and found nothing. Turns out the mounds were the remains of the root balls from the trees that were knocked down in that storm . I would not have wanted to go back to the department chair to explain this mistake.