You might want to consider doing a house hack to help you qualify for more.

So I'm seeing units being held back for longer... sometimes months to find a qualified bulletproof applicant.

If they're not willing to get on the phone with you and talk to you and talk business but also let you in on who they as a person then they a probably not worth a damn.I talk to people all day long, only 10% are qualified to get started tomorrow. 

"They are probably in sketch locations"- If by "Sketch" you mean anywhere in the inner city you would be right, however if being in the inner city alone doesn't qualify as sketchy then there are plenty of Section 8 rentals in low crime and very stable neighborhoods. 

Weeks later found another buyer, barely qualified, a pain to work with, does not respond half the time, red flags all over, seller is motivated.

They will have some questions and ultimately you can get pre qualified. 

If these groups are significant, it suggests there’s pent-up demand that could enter the market when one of two things happen:Rates Drop - Rates fall to levels that allow more buyers to qualify for the homes they want.Buyer Expectations Shift - Buyers realize that 5% rates aren’t coming back soon and decide to move forward.Based on the increase in activity I saw in Sept and Oct in my business, when rates hit low 6s, I'd say my market has plenty of pent-up demand. 

If you are looking to use rental income instead of personal income to qualify for mortgage, you'll be looking at commercial financing.

If you can't qualify for a Heloc, maybe you will not be able to get financing for the apartment purchase.

As long as the property generates enough cash flow, you may qualify based on the asset alone.Another route is to explore portfolio loans from local banks or credit unions.