Hi Aaron,
I would conduct keyword research in the normal way - search volume, competition, relevance for your wesbsite etc. Niches that are filled with spam are just like any other competitive niche - except the competition is easier to beat once you establish authority.
Once you have a bank of keywords that you feel would drive quality traffic, begin to work on producing quality content around them.
It will take work and patience to differentiate yourself from the spam. Building links from authoritative sources, press releases, social media promotions and generating quality content can help to establish the site as an authority on the subject.
The bottom line is that search engines and searchers hate spam. By differentiating your website from the spam and working to gain trust and authority, the chances are that you will be rewarded.
Best of luck!