Possible Clues:

• Person unknown or disapproved of
• An SOS form whatshisname?
• Forgotten his name, but thus he is doubly unpleasant (2-3-2)
• Desert covering old, old, forgotten person
• The whatsit for the SOS?
• Dirty dog, as it were
• That confounded person may be one of 20 down
• Difficult person
• Don's a complicated and extremely unpleasant person
• No sodas for this unpleasant person