dirty dog vs crumb

dirty dog and crumb both are nouns.

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

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

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

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

dirty dog (noun)	crumb (noun)
a person who is deemed to be despicable or contemptible	small piece of e.g. bread or cake
	a person who is deemed to be despicable or contemptible
	a very small quantity of something