Smuts carpet is fuzzy with hand drawn lines

Ok, does anybody else find the term “carpet muncher” totally endearing? I love it.

my 9yo drew on the wall and the carpet in his room he should know better right? then today i went in their room and my 8 yo has scraped his name into the wall what am i doing wrong that they do not understand this is bad behaviour? we use different discipline techniques we send to room /stairs take away privileges groud them. what more can i do they also constantly fight hit and call each other names and i just am at a loss.