I so agree....COVER YOUR HOLES, whether on the beach or land...cover them! Sure, folks go on the beach and dig big trenches and bury themselves and make sand castles with moats...and leave those gapping holes....but be the better person and cover yours! Our hobby is bad enough trying to get folks to give us permission...it only takes ONE for prospective place owners to say NO!!!
And if you DIG IT....KEEP IT! If it's trash, throw it away in a proper can...if not, put it in your pocket!
I carry a couple of plastic bags with me attached to my fanny pack

... and I put all my trash in there...the good stuff in my fanny pack!!
When the bag gets heavy, from all the BEER / SODA CANS I dig up on the beach....I empty it and start again!!! If no trash can available, I tie up the bag, set it aside and TAKE IT with me when I leave.
I love showing folks on the beach the broken light bulbs that OUR CITY leaves on the beach after the Christmas/New Years light show, the SHARP fence pieces, broken beer bottles that someone used to shoot off fireworks (which I cut my foot on, that's how I found it!!!), and other items! A good majority of them are shocked to realize all that is in the beach sands that their children are playing and walking on!! I've had many Thank me for picking it up and disposing of it!
I look at the place that I detect as if it was my own yard....but something my Father told me many years ago, "When you borrow something from a friend, take better care of it than if it was yours!" When you show and pay respect to the land and the owners of that land, you will get respect in return and possible future sites to detect....
And I agree...COMMON SENSE...it's gone, someone opened the door and let it loose and we can't seem to find it...but it's there, we just have to keep looking!!
YIS & YIMD,
Annmarie