I never have. It seems like that would wash the heads off, no? Basically ice hash but done at a higher temp. What if you have systemic pesticides? Might not even be soluble in water. Or if impregnated in the heads, so basically you would have to remove the heads which would make some nearly inactive butter.
Better to trust your source and not worry about it. I would not purchase any cannabis from someone I did not trust personally. If you gotta ask yourself that question when getting some I would suggest a pause.