The price of a loan is dependent upon many things, which are not magic but quantifiable.

It is easy to quantify and capitalize those costs.

- I'd love to see a study on smell in a house and the whole air-freshner thing vs. quantifiable appeal, but being very smell-sensitive, I strongly prefer no smell at all.

You and I could get the exact same phone call, and you could turn that call into $$$ while I might waste 2 hours on the phone and not make a penny.That said, I agree that the value of a call from a seller is impossible to quantify as well, as there is no way to know exactly how motivated the seller is, nor is it possible to generalize the situation the seller is in (every situation is different).

said, I agree that adjustments should be justifiable, either in terms of quantifiable data or qualitative relationships.

As you can probably imagine, that sort of thing is hard to quantify. 

The y should be written down, analyzed and quantified at least weekly.

It's a non-quantifiable variable which is why I don't work a deals' numbers to the decimal points because I might buy one house with a lower return if it feels like a good deal with a low hassle factor. 

But if you find the good one, there is a lot of room there to then be able to trust the system.But way more important than trust, because trust can't really be quantified, is the ability to verify.

Cash flow is not the only metric to quantify.