People are generally referring to this type of entry as contra-expense or atleast that's how I interpreted.In the PA tax return, this line item was highlighted in Red and hence the question

The south side tends to be a place where the people who make money are very rooted in the communities they invest in.

If so many people are considering it a "don't do" and multiple realtors are calling it illegal then why is it on the HUD and why are there specific portions of IRS regulations around how to do it properly?

I've heard stories about people saying because they source the deal and manage the properties, they get 50%.... 

The wholesalers wasting time is standard practice.

Us banks do it so we can make sure you aren't wasting our time. 

Never sell yourself short you have more properties under your belt then most people in their 30's.

While this is always a possibility, the reality is that VERY few people will actually trash a place.

Therefore, it seems this would be specific to the assets you have in your property.So a one size fits all percentage would be impossible to come up with.If people could put a percentage for the bonus depreciation there would be no need to complete the cost seg study.

Doing differently would be an opportunity cost.General partners of real estate funds are usually people who has a solid track record, able to provide the tax benefits, LT equity and cash flow you talked about.