dirty dog vs rotter

dirty dog and rotter both are nouns.

Word	Noun	Adjective	Verb	Adverb
dirty dog	Yes	No	No	No
rotter	Yes	No	No	No

As nouns, dirty dog and rotter are synonyms defined as:

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

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

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