Common fees will include a set-up fee, a leasing fee for each turnover or a lease renewal fee, marking up maintenance, retaining late fees, and more.

A turn key would be great, but I am open to doing repairs along the lines of walls and flooring updates.  

It's not fully closed as in drywall, it's sort of a faux wall on our side, but the tenant could open the door on his side and come through if he wanted.

Electric: is the easiest to split, but may require holes cut in walls to separate the units.Gas: gas lines aren't as flexible as wires, but it can usually be done affordably.Water: most cities will NOT install additional water meters on a property.

I would do some updates and add some color on the walls and maybe throw pillows etc.

Let's assume that the neighborhood is a C class and the median income of the city is greater than 3X of the market rent.Here are some of the considerations I've come up with so far:- Units are in need of renovation and capex is too high or not available- Unit quality is not the same as market - Seller is worried about losing tenants due to increase- Vacancy rates are high or filling units have been difficult- Rent increase would take multiple increases over multiple lease periods to get to market rate if seller is trying to retain the same tenant- Seller inherited property and just want to liquidate- Seller needs to liquidate quickly (financial burden, sickness, quick exit from land-lording)It seems like I might be missing a warning sign about a deal if they are selling with current rents that are under market; but again, this seems to be most of the properties I've underwritten.And in the same vein, what should I be worried about when purchasing a deal with under market rent with the intention of raising them after purchase. 

Focus on key areas first (like floors, walls, kitchen, or bathroom), which may help you handle the costs more gradually, even if it means moving in furniture or updating fixtures down the line.Also, since the tenant left it in rough shape, be sure to document all the damage (photos, receipts) in case you decide to pursue reimbursement through their security deposit or in court.

That does not exist on wall street without an insane amount of risk and volatility. 

In some older neighborhoods especially historic districts, the tenants look for older houses - they preferred the art deco bathroom tiles, the thick plaster & lath walls over granite countertops and stainless steel appliances.but class D neighborhoods are easiest to tell. 

Glazing in walls, enclosures or fences containing or facing hot tubs, spas, whirlpools, saunas, steam rooms, bathtubs, showers and indoor or outdoor swimming pools where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) measured vertically above any standing or walking surface shall be considered to be a hazardous location.