I handed the loan officer a Bigger Pockets calculator report and he unexpectedly told me he would give me an unsecured short term 90 day loan for the purchase price so I could do a cash offer.  

I will bet dollars to donuts the 18 month 0% is a credit card with teaser rate.or the guru has bought down financing rates from a unsecured lender.. which they pay for out of your 25k.

So the loan is unsecured until then. 

Unless the note is tied to a recorded Mortage or Deed-of-Trust (state dependent), then the loan is completely unsecured.

for you as the seller.OR you did not transfer title and your note is just an unsecured note tied to nothing.. or you did a lease option that ties to the property... either way you need to figure out what you did and did not do..  

Wells Fargo does an easy, unsecured, personal line of credit.

Same thing on unsecured business lines of credit if I remember right.    

A recent study of returns since the late 1800s found that unleveraged residential real estate outperformed the stock market on a risk-adjusted basis.

Technically these are just private loans as they are unsecured and not tied to the performance of any underlying asset.

Anytime you can leverage funds from anything regardless if its an unsecured LOC or a HELOC or a refinance its going to help you grow your portfolio.