This is commonly referred to as rental arbitrage.

For my single-family properties, tenants are responsible for all utilities.

Standard homeowner type mortgages are common.  

I am thinking about  replacing the floor for the common areas, bedrooms, bathrooms and private hallways for my rental in a nice neighborhood.

Granted MFH are more common in rougher parts of central jersey and my purchasing power can't acquire me something in North Jersey here homes are much more desirable when it comes to appreciation and schools and safety.

The $20k lots were near or in flood zones, steep slopes, rocky, woody and had limited or no utilities.

We utilized the VA loan, so we paid all of the fees associated with that and then paid roughly $3500 for closing.

Inflated ARV's and underestimated rehab costs are common practice with most wholesalers, much of which are newbies who have never flipped a home themselves.As another stated, there are other ways to land deals besides wholesalers so cast a wide net and use multiple avenues to funnel your leads.

What did you do with the utilities—did the city allow you to split them?

Remember to include the common area meter!