I have heard they can be dangerous or risky

Owning real estate is not near as scary and dangerous as people make it seem.  

Any less than that is dangerous, any more than that and that's money you don't have working.

I don’t think there is a real threat of danger, but you never know.

The liability of just adding cooking and bathroom spaces is dangerous.

It’s a danger that’s amplified when you choose contractors you’ve never worked with before, and it might jeopardize your house-flipping business strategy.There are various reasons why investors choose to invest in out-of-state real estate.

I think the pandemic moratoriums has set a very dangerous precedent that is too tempting for Governments to not again at any opportunity. 

Quote from @Justin Vom Eigen: Danger, Will Robinson!

It's crazy to see because 10 to 15 years ago these subdivisions were considered rundown/dangerous areas of ATL. 

They can be dangerous and should only be used for shorter term needs.A straight second mortgage is probably better, depends on the rental cash flow, interest is deducted.Another point as to refinancing any first, cash out may carry a higher rate and or points to cash out.