Possibly they want a thourough BPO for the price of a drive - by (at least a $20 differeence).
If on your "drive - by" yu happen to notice the place has been abandoned, you can can peek in the windows and try the door. There may even be a lock box on it already and you might be able to get interior access anyway. The previous listing (if any) may have interior pictures and possibly description of defects. You can certainly guess if there are broken exterior windows, trim, rotten roof, driveway buckling, dead landscaping, fallen down fencing, graffiti, green or black swimming pool water. etc.
As far as the interior is concerned you could speculate that due to the awful condition of the exterior, that it is likely that there are problems on the inside.