Then, if morals were no issue, (and we are discussing quick returns in business, so I assume morals are a minor considerationTongue out) I'd have to say prostitution- I mean the "companion" or "escort" business.

 

Seems to be thriving from what I can see at the Ramada and that place that used  to be beside the Marriott.  Sure I could expect more than a 15% return on my investment.  Sure that some with "manpower" contacts would be great partners in this business.... :-)