Physical Bugs

• The first and most obvious thing to look for are bugs themselves. Bed bugs like to hide in tight spaces, so check the seams of mattresses and under cushions. Look inside the screw holes with a magnifying glass and flashlight when inspecting a box spring, as bugs like to hide up inside these holes during the day. Check under cushions of couches and in the pockets of any used clothing you're thinking about purchasing.
  
  

Holes

• Look for holes, but keep in mind that holes may be made by a variety of different bugs and pests, such as mice. Bed bugs may be responsible for small rips and holes in pieces of cloth furniture. Look for tiny holes in mattresses or couches, which could serve as entryways into the inner fabric.
  
  

Red Splotches

• Red splotches are a telltale sign that a mattress is either currently infested or has been in the past. You may accidentally roll over and squish bed bugs at night while they're feeding or they could possibly leave a blood trail, resulting in small blood splotches on your sheets, pillowcases or your mattress.
  
  

Black Splotches

• You may find black splotches in the seams of mattresses where bed bugs often congregate. These splotches are the result of the excretion of fecal matter composed of digested blood. The splotches appear as spots on mattress seams and may be deep red or crimson in coloration. Never purchase a mattress with these black splotches, as it is a sure sign of either a past or present infestation.