He may also be genuinely hurt by feeling like what he does do is never good enough for you. If, every time he does something without being forced to, you say "Great! But..." then he will legitimately feel inadequate! Whether he's 5 or 12 or 25.
I would suggest the following:
1. Do not argue with him. If you tell him to take a shower and he won't, or you tell him to take out the trash and he won't, FINE!. Let HIM deal with the consequences of not taking a shower, having a rancid-smelling kitchen, etc. It will not kill him to miss a shower for a few days, and he's getting to the point where he'll want to smell good for the ladies anyway. If he won't take out the trash, then set the trashcan inside his room and go on about your business. Do not argue with him, do not threaten him. He is old enough to own his behavior, and if he is choosing not to shower or take out the trash, then he is also choosing to stink, and live with trash in his room.
--Make sure you talk to his teacher and say, we are having problems X and Y at home, and I am taking a new approach.. so if he comes to school smelling funny for a few days, I want you to konw in advance it's not neglect, I am changing my parenting strategy short-term.
.....Now, if at the end of two weeks he would rather sleep with trashbags and smell like a homeless person, than take out the trash, shower, and do his laundry, THEN you know something is deeply wrong with your son and counseling is in order!
2. Praise him when he does something good, and DON'T qualify the praise! In child-rearing, they always say give five positives for every one negative. If as you say, you are in a habit of saying "Thanks for doing your laundry, but why didn't you do the rest??" then your ratio is 1:1 and he will truly feel rebellious & angry for not being validated. Compliment him endlessly on his schoolwork. Acknowledge it when he does shower. Tell him how handsome he looks in a clean outfit. A 12yo is still a child and he still needs lots of love and validation from Mommy.
3. Give him a timeline... Tell him at 2 pm, "Honey, you have until 8 pm tonight to take the trash out." Remind him again at 5, and at 6:30 and at 7:45. It is win-win. He doesn't feel like he has to drop everything and do it immediately (and except for in extreme cases, Mom, you really don't need that from him. HOnestly, you sound just as stubborn as he is.) And you still get the trash taken out. Hopefully. But if he doesn't take it out, then set it in his room! He doesn't have to do your laundry, but make him do his own.
4. You seem extremely rule-oriented. Thing about kids is, they all go through a stage where they want to be the opposite of their parents. The more you try to impose your will, the more he will fight it. The strategies above will give you a break from feeling like a dictator, and will give him the chance to succeed or fail, without judgement either way.
5. I have a child who often laughs a very nervous, weird laugh when she is being spanked or gotten onto. This is a nervous reaction. It does NOT mean he was feeding off the argument. It could simply mean he is nervous & upset and those feelings are coming out in a strange way. Hell, I had a laughing fit at the altar, they had to wait 5 minutes to start my wedding ceremony (to the N) because I started laughing uncontrollably. I had to sit down, in my wedding dress, cuz I couldn't stop laughing! Laughter does NOT mean you feel great, necessarily.
You DO need to acknowledge his accomplishments you DO need to let him brag, Mom! That is not a bad thing!! He does not feel validation from you! He's a CHILD! It is kind of a big deal for most 12 year olds to do their own laundry, honey. The more praise you give him, the more he will want to please you.