dirty dog vs scum bag

dirty dog and scum bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
dirty dog	Yes	No	No	No
scum bag	Yes	No	No	No

As nouns, dirty dog and scum bag are synonyms defined as:

dirty dog and scum bag: a person who is deemed to be despicable or contemptible

Other synonyms of dirty dog include bum, crumb, git, lowlife, puke, rat, rotter, scumbag, skunk, so-and-so, stinker, stinkpot.

dirty dog (noun)	scum bag (noun)
a person who is deemed to be despicable or contemptible	a person who is deemed to be despicable or contemptible