What if the business is illegal and is just cash, like drugs, prostitution or gambling?

http://www.biggerpockets.com/forums/88/topics/110211-is-25-a-good-cap-rate--gambling-on-appreciation

Every time you move new tenants in you gamble on getting horrible tenants.

Hey Bill-So would you say that wholesaling is a fraudulent activity?

Thanks again if you dont get anywhere, you can see if you can buy the lien, then take the gamble on if you can finish the foreclosure process.

Borrowing against retirement money is also a bit of a gamble for at least two reason:1.

In my opinion that is speculative investing, and I am not much for gambling.

For example you can look at alternative acquisition strategies like seller financing or lease/options (L/Os can be really risky though, cause you're kinda gambling with the seller on appreciation). 

Avoid online auctions if you like to gamble, and can't resist putting in "just one more" bid.3.  

I have been searching and these are the kind of houses that I am seeing on Craiglist, MLS, papers, etc..30K older homes in C/D neighborhoods that will rent out for about $575 - $650 with $5000 worth of renovations.70 to 100K 70ish homes in B/C neighborhoods that will rent out for $850 to $1200 depending on price and other variables.100 to 250K 80/90 ish homes in A/B neighborhoods that will rent out for $1200 to $1800 depending on price and other variables.Duplexes seem non-existent or as the podcast gurus have said are a "Waldo" property with too much downside to take a gamble.