I suppose 더럽게 재미없다 Literally means something 'dirtily lacking fun', so the meaning in more natural English is something like 'absolutely not fun'.
Does it seem natural to say '더럽게 재미았다' for something that's very fun?
You would say 더럽게 재밌다 for being sarcastic, "I don't want to admit this, but it's pretty fun."
더럽다 doesn't pair well with anything positive.