Why do dustcoin.com and coinwarz.com give opposite results of profitability?
First off, don't listen to so called "profitability" calculates they are always wrong.

and here's why:
Each "profitability" site bases the profitability based on the current block on that network vs bitcoins current block. Well most of these coins have a limited exchange volume on exchanges (some as low as 0.001 btc) yet because of that activity they are deemed to be more valuable. What happens next is a huge dump of coins and a market crash. This leads to an increase in diff and a decrease in profitability. Using that theory, you can see that these sites are not going to be correct. Especially depending on the exchange they use and the rates they use. Most coins only convert from ALT->BTC. So that means they will take the BTC/USD price from somewhere like bitstamp and then take the ALT/BTC price from the exchange of choice and finally it will take BTC*USD.

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Simple formula these sites use

$profitability = $USDperBitCoin * $BitCoinperAltCoin

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tl;dr
Exchange rates and exchanges used.
Low volume of trade.
Unique Difficulty filter algos on unique coins

I suggest you ask the owners of the sites this one.