Hi
The first time I was told to look at a sticky board I was unable to make
head and tail out of it. However I pretended I saw them, not to feel stupid
in the presense of the " experienced "  multitude of beekeepers.
Is really immaterial how much other debris is on the board, ONCE you are
able to SEE / indentify  the mite dead or alive [ And they are rather quick
if not stuck] you WILL  see them. Depending on you vision factor you might
use a magnifying glass to separate the grain from the chaff.Of course,
should you have no mite infestation , you will not spot any or have a hard
time finding the odd one among the other junk.
catfish