Sweating feet usually means either your boots are too heavily insulated, too tight, or don't breathe well enough.
My wife complained 2yrs ago because her feet got REALLY cold in a pair of boots that she had worn in the cold several times. The only change she made was that she had put on thicker socks (or two pair, my memory isn't so hot). Her boots were just a bit too tight, didn't let air circulate, and she her feet froze. Same boots with only one pair of normal is good to 20below (about as cold as it ever gets here).
Pretty hard to keep your feet warm in rubber boots as well, because there's just NO air movement in them, so the sweat has nowhere to go, soaks through your insulation (and socks) and becomes a heat sink straight to the outside shell.
Or, of course, if you're wearing 2,000g pack boots on a 40degree day, your feet WILL get cold. You're going to sweat like crazy, soak your insulation, and sink heat away from your feet.
Call me a sissy if you want, but for what it's worth, I use boot/toe warmers. Most of the time I wear rubber "hog boots" (tall stove all rubber boots) while hunting, they cost about $20 at any farm supply store. I keep two pair, one that fits my foot in a normal crew sock for warm weather hunting, and one that fits with a crew sock and wool sock on, plus a toe warmer. The rubber boots and wool socks will keep me warm in ANY weather if I'm on my feet, and are good down to single digits to mid teens in the stand. Add a boot warmer, and take them off once a day and they're good down to 40below (about as cold as I've ever hunted them).