A detector will not sense a non-ferrous object (like a scoop) unless one or the other has movement. Since the coil pulses equally below the coil plane as above, avoid placing anything metal along that axis. Typically, you keep the scoop away from the coil just to avoid the initial squeal. The larger metal mass of a scoop may also destabilize the balance and cause a wandering tone as the detector loses null.
If there are a variety of random pops it is likely man-made interference or, if late in the day, it can be distant electromagnetic pulses from lightning (which are vertically polarized and show up when the detector coil is vertical, e.g., the detector is set down). If you hunt early and noise cancel at the start, when it's dark out, it may be necessary to noise cancel later when people wake up and start putting out EMF (the TV and microwave come on). Stopping to noise cancel every 30-40 mins wouldn't hurt, especially if you're hunting near population centers.