I remember my brother telling me that all of his winnings that he earned through gambling is called "dirty money"
Like others said, It really depends on how does a gambler earned it. Literally speaking the money you earned from gambling is called "Dirty money" but the idea behind that, is that it is passed from one person to another. Ethically speaking, that money is not dirty if you earned it by your own way and without any trace of dishonest act, or cheating.
I think every greedy person has their ways like they value the money
Like crwth said, we all have different perspective in regards money. Whether it came from good and/or bad.
Though, we need to accept the fact that all our decisions has its own consequences. It maybe a positive one or a negative one.