Since scum is what rises to the top, I suspect it is better applied to others.

Steve Bell had a very good parody of "Feed the Birds" on his cartoon on Saturday, which I will seek out.

Found instantly...

"All around the Cathedral the pigs and the fat cats look forward to clear each tent,
And though you can't see them you know they are laughing at a rise pushing 50 per ce-e-e-e-ent.
Feed the Rich, 2 million a bag etc etc..."

Which also counters my own perception that the right tend to use dismissive insults of those they don't like more than the left.