Here are some tests (over many years) I wish I had thanked the judges and walked away from:
Started Mark toward a busy highway.
Senior Trail toward a busy highway.
Water mark with one Over-Under and a third mark with an entry into a deadfall with potentially dangerous sticks.
Into-the-wind triple where there was equal access downwind (following a screwed up land series.)
Upland tests quartering into "blockers." (X n)
Upland with flush at the end a long trail.
Marks into 6 ft. cattails.
"No-see-em" water blind that was technical enough w/o a trick.
The ones that come to mind were either potentially unsafe or unfair to the dog (at the level he was at.)
Misteaks happen, judges only make my "list" with repeats.