Gun shops don't have a monopoly on "Sh*t you see"....
Try working as a range officer right before hunting season opens.....
Everything from new guns with scopes on backwards to old timers with a dusty box of shells checking the old ought-6 for minute of paper plate accuracy.....
Amusing...frustrating...and down right scary...all at the same time...
I did it for three years when I first retired.....that was enough to last a lifetime.....
I was working sight in weekend one year at a range. A good friend was working at the bench with me and his shooter could not hit paper at a hundred yards. My friend looked at the scope to make sure it was tight and checked out the rifle then discovered the shooter was shooting 25-06 out of a 30-06.
From then on we all checked the rifles nd the ammunition before letting anyone shoot.