Some lines and/or polygon fill shades appear transparent or streaky.
The linesets and shadesets such as PLOTTER are 'stroked' symbolsets. The shade/line is potentially not completely opaque, allowing underlying features to display through.
Solution or Workaround
Use SHADEPEN and SHADESIZE or LINEPEN and LINESIZE to assure that stroked symbols are wide enough to eliminate the streaky appearance. A good rule of thumb is to set LINEPEN = LINESIZE (or SHADEPEN = SHADESIZE). Continue increasing the size of these parameters if problem persists as the 'stroke' of the symbol may still be too narrow.