1.   Even then they missed considerable stretches of gutter with accumulated dirt.

2.   For the past few decades, because of the accumulated dirt, it was difficult to see the resemblance between the figures and their monikers.

3.   How difficult is it to remove accumulated dirt from the machine you are considering?

4.   With eraser shavings, a Q-Tip and magnifying glass, she painstakingly cleaned each piece of artwork, removing decades of accumulated dirt.