Couches are two tiles wide, and are always horizontally aligned, and are always facing north (see picture).
Couches may be bugged, assuming Max has at least one Bug left in his inventory. To do this, walk up to the couch and press the "F3" key. Remember that only one Bug may be installed in each room.
Unfortunately, the value of bugging couches is directly opposite to their prevalence: At best, bugging a Couch in an Office or Storage Room will give a +4% Surveillance Quality bonus. At worst, bugging a Lounge gives only +2% Surveillance Quality.
You can hide behind a Couch when crouched, and can also jump over it if necessary.