Bees for a Sugar Roll?

[Rurification]

In the directions I have for doing a sugar roll mite test, it says to get only nurse bees from a brood frame.

I have supers on right now, but the bees are bearding like crazy in this humidity.   How off would my numbers be if I just got a cup of bees from the beard instead of going inside and doing a deep inspection and pulling a brood frame?