What do you do when you get a fresh snow on an existing dirt hole set?
Leave it alone, only open the hole back up, sweep off the entire set, or something else?

I usually sweep off because of freeze/thaw is common in my area.

I use salt, lots of salt so I don't have to worry about snow
I prefer to set with snow in the forecast, I think it helps cover some of the human scent we leave behind
And the ground won't freeze with a powdered snow on top of it
Just my observations

Are you using salt to prevent any snow from accumulating on the set or using salt to keep your trap from freezing up?

If you are using freeze proof dirt I would leave it. Natural blending. You have lure and bait there so you have that attraction. As long as your trap is able to fire and reach through the snow.

Both, under grass covered traps to keep them working
Under and above dirt covered set to keep them working and added eye appeal
I also salt a dirt hole or poke holes to keep them from freezing shut
Salt's cheap, waxing dirt isn't

Depends on how much snow. I usually brush off. Tomorrow we're supposed to get 18 inches. Our freeze/thaw has been extreme again this year. Had 3 feet of snow a couple weeks ago. Then a thaw right back to bare ground. Few days ago we had rain that turned to freezing rain to wet snow. We got a foot of that right now. Sometimes impossible le to trap. Snares are not allowed
You can't use enough salt for our lake effect snows.

salt will rust your traps like you wouldn't believe. Chain, too.

Only if you make a catch
And then it's easy to nutrilize the salt with a baking soda bath
I've been doing it for years now with no problems

Round here, I’m hoping it’s snowing as I’m setting. This morning I just cracked the sets on the sled trail loose to make sure they’re still functional and barely dusted them, they’re still visible after we went over them. Can guarantee they’re covered within 5 minutes as there was some blizzard action today, just have to make sure they’re set where it won’t drift in. Good times!

As long as I’m confident the set is still working under the snow, leave it alone.

If the snow is of a type and amount to not impede the function of the set or trap, leave it alone.

If the snow conditions aren’t going to change in a way to impede the function of the set or trap, leave it alone.

4” of cold dry snow is not the same as 1” of heavy wet snow.

If it’s gonna warm up and melt before I get back to that set, may as well get the snow off that set now before it has a chance to make everything a mess.

This
Like Shakey, I like to set when it is snowing or just before. Nothing blends a set like a fresh covering of snow, and it is very difficult to clean it off and make it look natural. But the set has to be working or it doesn't matter what it looks like.