1.  Look for ex-grow op homes:
Whether these homes had an ex-grow op last year or 10 years ago, these homes often fetch below market value.  No buyer would buy an ex-grow op home, when a similar home sells at the same price, hence, you can often use this stigma to negotiate the price below fair market value.

2.  Court Ordered Sales/Foreclosures:
The reason these properties went into foreclosure is not important.