A student who says they don't like art and who constantly disrupts could be "saying" any number of things that have nothing to do with art:
1. "It doesn't matter if you are mad at me or are laughing at me, I love to be the center of attention."
....Find as many ways to give positive attention to the child as possible. Also, it will help to take away the child's audience: use a buddy room or let them sit in the hall with a written assignment until they decide to behave in your class. Attention seeking is the most common reason for upper elementary or middle school students to misbehave.
2. "I am really, really bad at drawing/painting/etc. and I don't want anyone to know just how stupid I am at anything related to art."
.... A student who is convinced they are bad at art can be dealt with in any number of ways. Give the class non-objective assignments (see below) or keep changing up the medium to find what the kid might excel in. Teach the students (all of them, not just this one student) the Growth Mindset (here are a few resources). The only difference between a master and a beginner is the number of times the master has failed. DO NOT allow the child to complain or say negative things. This habit is toxic and can infect the atmosphere fast! Rule Number One in my class is, "Be Respectful." That includes being respectful to yourself. No negative self-talk.
3. "I like to complain and I will complain about anything and everything. The world sucks. You suck. Everyone sucks."
.... Have this student practice positive thinking and speech patterns. Even better, have the entire class practice so the student isn't singled out. Again, DO NOT allow complaining. It is toxic. There is a chance this child needs to be referred to the counselor, but more often than not this kid is just suffering from a negative mindset. One magical activity to do (OFTEN) is to have students write an encouragement on a Post-It note and place it on a neighbor's artwork. Middle school students especially are desperate for encouragement!
4. "My home life is pure chaos and I don't understand how to handle anything right now. Everything is so confusing and I am furious about it!"
....A heart to heart talk with this student will hopefully begin to uncover anything under the surface that the student needs help with. Consider referring this child to the counselor.
5. "My parents hate me; I am told every day what an awful/stupid/worthless/etc. person I am. There's no point in even trying to do right because everything I do is messed up anyways."
....Refer this child to the counselor. Constantly seek to build this child up with encouragement, attention, or anything else you can do to help.
If it is realism you are after, have the kids do a before-instruction drawing to compare the after-instruction drawing to. If they can see growth, you've won.
One lesson that I continue to see benefit all my students is a non-objective drawing with markers. My goal was to get them to appreciate non-objective art/artists, to choose a style (geometric or organic), and to improve their craftsmanship.
We also talked about how "line" can actually communicate in a work of art! Vertical lines can symbolize strength and dignity, diagonal or zig-zag lines carry a lot of energy and movement, while horizontal lines are very restful (but can be boring). In addition, zig-zag lines can mean anger or danger (they remind us of lightning) while curving lines sometimes symbolize happiness and joy.
We compared and contrasted Picasso's "Weeping Woman" with Matisse' "Woman In a Purple Robe" to see how their use of line carried emotion! A few other artists we discussed were Kandinsky, Mondrian, Pollack, and Stella.
When the students were asked to draw with black line, I instructed them to choose a style and type of line that matched their own personalities. It was amazing to see the different pieces they created! I also asked them to use no more than three colors, repeating them throughout the design.