What is this?

Those are pre lubed, lead bullets.
Taking the grease off will cause leading in your barrel.
Unless you were going to powder coat them...

They don’t look very well done, or perhaps dirty?
Maybe a redo through the Lubri-sizer?

People who cast their own bullets have to buy a sizer lubricator to lube bullets. As long as you have those, you don’t.
https://www.amazon.com/Lyman-4500-Sizer-Heater-115-Volt/dp/B000N8LCP6

Don't try to clean that "grease" off, It's bullet lube and needs to be there or you will have a mess to clean out of your barrel.
Like Demi-human said, it's bullet lube.
If you only paid $10.00 for 10 boxes of those you got one hell of a deal!
Load them the way they are and just go shoot them.
All lead bullets must be either lubed or coated with something to keep the lead from contacting the barrel or your barrel riflings will fill up with lead.

The hollow base on those bullets will conform to your barrel very well and seal, and with the lube they should not lead at all.

Those bullets are meant to be loaded light loads our you could blow off the skirt and leave it in the barrel for the next bullet to hit.

They are very accurate with a good light load and out to about 25yards should shoot extremely well.

Some lead bullets have a lube groove you can see and it will be full of bullet lube of some color and some bullets like the ones you have with the cross hatching on them has a different kind of lube on them like Hornady swedged bullets that's transparent. In fact, that box almost looks like and old Hornady box. It's the right color anyways.