as clear as mud

:  bright, luminous

:  cloudless

:  less than one-tenth covered

:  in a clear manner

:  all the way

:  to make clear or translucent

:  to free from pollution or cloudiness

:  to free from accusation or blame :  exonerate, vindicate

:  a clear space or part

:  a high arcing shot over an opponent's head in badminton

:  a slimy sticky mixture of solid material with a liquid and especially water

:  soft wet earth

:  abusive and malicious remarks or charges

:  to make muddy or turbid

:  to treat or plaster with mud