All grades of buds can have nasty chems in them, because most people don't rank cannabis by what the grower puts into it. This information simply isn't available unless you actually know the grower. Most people don't know what's in their tomatoes either, even the Organic ones. They just pick the pretty ones.

You may be able to wash of some sprays if the bud has just been freshly cut, but funky nutrients leave salts and other non-smokables inside the plant's tissue.

I'd eat it before I smoked it. Green Dragon is a good idea as well.