You probably shouldn't go for dirty water unless you are absolutely sure it has a positive effect on the species you are going for and are confident you can keep it stable on the "˜dirty values' .
It's not because a coral is hardy and does ok in dirty water that it wouldn't have thrived in better waters. Besides, you will notice a bigger difference with good/bad lighting and water movement than with slightly elevated nitrates.
My personal experience with euphyllias (except glabrescens) is that they survive much abuse and are very adaptable but they remain stony corals and you should aim for perfect water values.