I hear about that, but have never really seen that with my tools. I use a modified Zenport grafting tool for grafts and never clean it. I don’t see any buildup on it. Maybe it’s the tool?
For fall budding, I use a short blade knife. But again, I don’t experience any buildup on it. I don’t have it handy to take a pic of it. But I don’t recall ever seeing sap on the blade. I’m talking T-buds here.