Theoretically, I would guess an ADU adds value to the property because there is an additional income producing unit. 

To be worth the effort, it should produce return significantly greater than passive options.  

I just created an income producing asset creating $600/month in positive cash flow with none of my own cash invested.  

And if you're investing in a syndication that typically produces K-1's late in the tax season (such as a GP fund) this can make things very tight and/or cause extra tax bills from having to do estimates extra tax work with your CPA.  

Fortunately the appreciation has produced outstanding overall returns.  

To your second part of the question: Most multifamily will be tenant occupied, which means they are producing income.

Can you offer tips that aren’t going to produce properties that are on every list imaginable?

It's not often that a low producing property recovers that much.  

.-- How many active tradelines produced that credit score?

The property produced $48K gross over the past year.