Do lenders view seller carry backs at the closing table as unethical?

They do not have one so I will need to go over all the details to make an offer based on info I can get from the seller."

SUBJECT TO existing mortgage of $125,000CASH TO SELLER $10,000WILL REFI BEFORE TWO YEARS ONCE PROPERTY IS STABILIZED (I deal with local community banks and will do a commercial in my LLC to cash out at 70% LTV to recoup back some of my initial investment?)

As a buyer, what is the largest "repair credit" or cash at closing from the seller you have seen be approved for a FHFA loan?

However, when John Doe dies and his daughter Sally Doe, the successor trustee is selling; then it is referring to it as a trust sale.The trust sale refers to any property where title is held by a trust and the trustee (or successor trustee) of the trust is the seller. 

The seller accepting means almost nothing in a short sale process.

Then it's up to the seller(s) to get the squatter out.

I spoke to the owner of an abandoned house and she is very motivated to sell.I am prepared to make her an offer however she informed me if an 150K tax lien from the IRS. 

Since they were already willing to seller finance, I am hoping you guys have some additional ways to counter to make this a good deal and to verify that my current analysis looks okay.

ARV = $110,000 * 70% = $77,000- Repair Est: $30,000 = $47,000- Wholesale Fee: $12,000 = $35,000 -------Mortgage: $21,000+ Back taxes: $7,500 = $28,500+ Cash to seller: $4,000 = $32,500------Problem: the house hasn't been probated yet.