Searching for spilled/dropped drugs on the floor.
May be a leisurely pass-time amongst pot-heads, and can appear to be an obsessive compulsive disorder for cocaine users; the extent to which it is an enjoyable and fruitful activity is dependent on both the drug and the circumstances.
Less frequently, "window shopping," which is often more in line with the tendency to get nothing.
See also the Fabulous Furry Freak Brothers strip in which Phineas constructs a home drug recycling machine with which to sort out the sweepings from the Freak Bros' rug.
You know things are dry when even the dealer's going floor shopping.