It allows me to preserve my margin, have the money to continue repairs and prevent an issue where the tenant becomes so below market that you lose them to raise rents to market level.

It defers the payment, we earn (marginal) interest on our funds, and we get 1% cash back on the card we use for business - just paying the insurance on our rental portfolio each year yields a decent return (and we self-escrow the funds for insurance, so the money is there to make the payments). 

Don't chase the highest/maximum/ideal profit margin. 

I've seen it said that mold, asbestos, lead, etc... just spreads the profit margins greater in a very good way!  

Regardless, if you are not risking any money on the deal start with high margins and work your way down...  

I disagree.CAP rates are of marginal truth or consequence for a SFR.  

It had a huge profit margin and mostly cosmetic work, priced very low even for an REO.

If it's a marginal deal or not much EM at stake then might want to walk.No legal advice.       

Unfortunately the back taxes are so great that when you combine the rehab cost there is no margin for profit.

Specific to your post above, I agree that that $300 margin doesn't account for property management, any expenses, etc.