I’d be curious to know if it’s just my solder. I’ve always used the same stuff. The main mess I have is clear flux blobs. They are tiny, but you can see them if you get it at the right angle. (They’re also always crusted up on my thumb and pointer finger of my left hand 
). Occasionally there will be some excess flux around a pin. Both come off easily with a few cotton swabs and patience. However, once you multiply that by 60 or 87, then it becomes a pain. It’s supposed to be “no clean” rosin core flux, but I’ve always heard you still need to remove it or it will corrode over the years. And that makes sense b/c flux is supposed to corrode… that’s part of it’s purpose.