VG-10 is very good at corrosion resistance, for the most part. I have lots of VG-10 knives, and about the only corrosion I get is some very slight discoloring that forms in the well of the lock (in a lock back). It doesn't affect the lockup at all, it's only slight surface rust, due to the rougher, unfinished surface in the well of the lock. It really can't be cleaned out, and like I said, isn't a problem other than perhaps 'cosmetic', and even then, I never check the lock's well unless I'm checking for pocket lint in it. Sometimes, too, the tiny spaces between the jimping on the back of a blade may discolor a bit, too.
I once got a spot of discoloration in the blade of a D4 when I took it out of a sweaty pocket without wiping it, but I easily removed the spot with a pencil eraser, with no trace of it left.
I may be unusual, but I've gotten actual rust spots on 420HC on a few Buck knives, on the blades and inside of the backsprings, simply from pocket carry. They required a bit more work to remove than the little spot I had on the VG-10, and I still had slight traces of stains where the rust spots were removed. And my sweat is not especially acidic.
I consider VG-10 to be excellent steel. Some call it a lower-end steel, but I disagree. Twelve years ago, VG-10 would have been top-of-the-line. It might not be "the latest-greatest," but IMO it will do most of what any great knife steel will do. If I took a knife into the seawater, I'd take one of my Salts, but that's not an everyday thing for me.
Jim