Is this a valid concern, or does it happen so rarely, that nobody worries because the benefits outweigh the risks?

@Adam BinderYou may want to check this HUD document to make sure the LCSW email is valid.   

You signed a (presumably valid and enforceable) contract stating that you would buy the property and tendered a deposit to bind the contract. 

Also are they giving you a standard warranty deed (whatever your jurisdiction calls it) or a "special" warranty deed? 

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In our area you can evict for not having a valid lease, or any other cause other than non-payment.

Then once one is unofficially chosen, the background and credit checks are used to validate everything they stated in their app.

Just a some of things you might want to look into to ensure you have a valid contract for occupancy (in addition to complying for Fair Housing Laws).Good Luck! 

For maintenance, I had a home warranty on every property.

If it was purchased new like he stated - then he needs to go to the carpet Installers to look at their warranty and get it redone.