An illegal junkyard is one which is either:
(a) Established or is maintained in violation of this article and does not come within the definition of a “nonconforming junkyard,” as defined in Section 746.1.
(b) A junkyard which becomes visible due to inadequate maintenance of screening located off the highway right-of-way, or the placement of junk so that it may be seen above or beyond the screen, or otherwise becomes visible.
(c) A junkyard which, due to any conditions other than those described in subdivision (f) of Section 746, is established or maintained in violation of this article.