You didn't say how old your son is, but I think it has to do with the age. My little girl is 3, almost 4, and she hates to have her hair brushed! She refuses to keep socks or shoes on, and absolutely loves to play in the dirt and mud with her brothers. Thankfully, she enjoys taking a bath and brushing her teeth (her way, of course). When it comes to dressing, putting on socks and shoes, brushing her hair, or any other task--no matter how mundane--she laughs and runs away, or jumps up and down, falls on the floor.... anything to make it impossible for me to accomplish the task. And asking her to do it herself, well....sometimes she does, mostly she doesn't. Kids that age don't understand why they should be clean, they don't care if they are dirty or if they smell. Those things will come in time. In the meantime, pick your battles. For example, because my little girls hair is naturally curly, believe it or not I do not brush her hair everyday. I just spray a little detangler and run my fingers through it quickly. And on the days we are at home, I don't put socks and shoes on her.
On the other hand, one of my little boys is 6 and appears to have a few problems with sensory integration. He absolutely hates to have his teeth brushed because he doesn't like the way it feels. While I do attempt to get him to brush his teeth, I am lucky if that happens one time a day. I have found that he will use the oral B "brush ups" to wipe his teeth, though. Not nearly as good, but it definitely helps with the bad breath. He also refuses to let me brush his hair because it "hurts." In that case, we simply decided on a buzz cut. He loves it--he wanted to be bald--and there's not enough hair to worry about brushing. As far as shoes go, he is far more likely to wear them if they are slip-on and don't require socks.
My point is, find ways to compromise with your son--unless it is a battle worth fighting. I always think: is this something that will negatively affect him in the long run? Is this something that will keep him from being a happy, healthy adult one day? I the answer is "no" then I let it go.