Hi Amr,
A while ago, inadvertently, I misspelled a word in the name of an html file. This was for a pretty competitive keyword (tons and tons of Google results). When I typed the misspelled keyword into Google, I was amazed to find that I was #3 on the Google search results page. However, when I typed the correctly spelled keyword, my page was way way down.
I think it comes down to competition for a keyword. If you're competing with millions of other websites for a keyword, it would take time and a lot of work to be on the first page of the Google results page. However, if your page is optimized to the misspelled keyword, you might do better, because your competition is less.
I used to see products that could help identify "profitable" misspelled keywords. I am not sure this would be a good long-term profitable strategy, especially that if you misspell a word while using Google, it will always tell you... "Did you mean [correctly-spelled word]?". Then, most people will realize they misspelled the keyword and click on Google's correctly-spelled suggestion.
Anyway, I know I rambled and I haven't really directly answered your question

Not sure if others would agree with this, but I don't see anything wrong with capitalizing on the traffic from the misspelled word. In the meantime, I would still work towards bringing traffic using the correctly-spelled keyword.
Sherif