Most lenders want to understand the sources and uses of funds in the transaction.

All the purchase transactions i dealt were investor centric and Passive income / Positive cash flow oriented. 

Where a broker comes in very handy is handling the offer and the transaction.

At first it sounds like typical, corny corporate-speak: PM business is relationships, not transactional.

They are negotiable but the realtor will have to pay that fee at a minimum to their broker upon closed transaction. 

We're talking about title company reps, real estate transaction attorneys, SEC attorneys (yeah, the fancy ones), insurance agents, and lenders who make magic happen.

It was not uncommon that they bought some of the worst houses (weird layout, dated, much deferred maintenance) in the nicest neighborhoods and then would try to relist them as-is to make a profit before ending up having to do the actual work required to the property for it to sell again, selling at a loss, or maybe making a little bit of money in transaction fees.

Most lenders will allow up to 75 maybe 80% loan to value on a cash out transaction for an investment property loan. 

I'm glad MLS's (and Z) are cracking down on "grey transactions" that come across as possibly predatory deals. 

As an agent, I always tell my clients, you do NOT need an agent to do a transaction.