(defun SelectNotPlottableInserts (/ ss)
  (if
    (setq ss
           (ssget "_X"
                  (list
                    '(0 . "INSERT")
                    (cons 8
                          (str-untok (NotPlottableLayerNames) ",")
                    )
                  )
           )
    )
     (sssetfirst nil ss)
  )
)

(defun NotPlottableLayerNames (/ o l)
  (vlax-for o
              (vlax-get-property
                (vlax-get-property
                  (vlax-get-acad-object)
                  'ActiveDocument
                )
                'Layers
              )
    (if (= :vlax-false (vlax-get-property o 'Plottable))
      (setq l (cons (vlax-get-property o 'Name) l))
    )
  )
  l
)

(defun str-untok (ls c)
  (strcat
    (car ls)
    (apply
      'strcat
      (mapcar
        '(lambda (s)
           (strcat c s)
         )
        (cdr ls)
      )
    )
  )
)