Do you need the explanation of the source of down payment, or in other word, the history of the source?

Understanding one's market is step #1 in my opinion.Check out this article for a more in depth explanation of wholesaling.https://www.biggerpockets.com/renewsblog/2015/01/31/ultimate-beginners-guide-real-estate-wholesaling-2/?

This has been extended 3 times and going on 4th with no other explanation other than we are working on it (the tax lien). 

I finally got approved and the approval letter with the numbers does not make any sense at all, I asked for an explanation nobody can explain it to me.

I would get rid of him and move on, and chalk this up to learning.In the future, you might consider what we teach our clients:In 5 days, everyone on the loan gets a phone call, and an email reminding them they are late and asking for immediate resolution.In 15 days, everyone on the loan gets a phone call, an email, and a letter, demanding payment that day or an explanation of why they haven't paid and how they will correct it.

The common approach I've seen for a list of addresses of buyers is to send a postcard with an intro and brief explanation of what I'm trying to do for them.

Some things that come to mind are adaptations to some things buyers might do in a competitive bidding environment: Submit a letter of explanation to the buyer's agent explaining how you love the house and will find the perfect tenants/next owners/etc.Be the first and best offerPresent a no-strings-attached gift with the offerI'm curious to hear other suggestions.  

. - I'm having trouble following your explanation.  

What satisfying explanation can I give them?

@Joel Owens, thanks for detail explanation.