One thing to note when looking at the individual markets, you can make or lose money in any market.

Completely renovation the kitchens, fresh coats of paint throughout, stainless steel appliances, new toilets, lighting, Ceiling fans in every room, removing the baseboard heat and adding individual room heaters.

Also for those that house hacked fourplexes it would be awesome to talk to you individually!

I ran a meetup group for some time and also started a membership sports club successfully so have a little background :)People enjoy fellowship with like minded individuals so be sure to build in that personal touch, and go out of your way to welcome new members and introduce new members to others.

Feel free to DM me if you'd like some suggestions on how to due-diligence individual deals, sponsors etc.

Duplexes that are sold individually and parceled differently aren't called duplexes. 

As far as backing out yes you can request your Escrow deposit back during the inspection period for any reason you deem fit, many individuals will say it is a free look however professionally that not the best description since it is not free, with any due diligence you invest in inspections and other professional services to answer as many unknowns as possible to remove as much risk as you can prior to purchase.

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I'd also suggest looking at some broad metrics regarding profitability (cap rate and cash on cash return) which will help you compare individual properties relative to other options.  

Like what Nabil mentioned, you may not able to recoup your losses if he has no assets or trail of any assets.If you signed the contract as an individual, you can get help from the city attorney when you file a lawsuit and present the case without attorney representation.I hope that helps, good luck.