How are you removing the fresh dirt smell in the trap bed? I know in the right conditions you can pound in a bed rather than dig it, but you still need to cover the trap.
This method is for conditions where your surface dirt is dry maybe down an inch or so,
but below that the dirt contains a good bit of moisture and the smell that comes with it.
The fresh excavated dirt from the bed is left on my tarp.
Dry surface dirt gathered from the immediate area replaces the fresh earth from the newly dug trap bed
Keep in mind the bottom of the bed still holds that telltale smell of fresh dug soil.
Filling it with dry dirt will help pull out moisture from the lining of the bed so the smell will better blend with the neutral smell of surface dirt on top.
When the set is done the tarp is gathered up with the fresh dirt and slung in the air to disperse it over a wide area.
Keep in mind in some cases replacing the bed with dry is not enough to negate the fresh dirt smell of the lining of the bed.
This usually happens when there is an abundant amount of moisture below a dry surface, usually after a recent rain.
That type of soil condition will get you dug up quick.
There is a way to fix that problem, but I will keep that particular one under my hat for now.