Shoddy or delayed repairs.

Before you rent, open all the cupboards and drawers, look for tell tale signs of pests. Feces or dead bodies, hairs.

The longer the list of what you're responsible for the less likely you'll get your security deposit back.

Not letting you take pictures while inspecting an apartment.

Check all the drains and faucets, flush the toilet. Make sure there's good water pressure and drains are cleared.