Guards don't try and arrest me anymore. And they randomly attack me. I'v murdered a few people I didn't like or for fun. Never been cought. I steal everything in sight. Is my karma super bad or is this a glitch?

from what i know it sounds like a glitch

Your bounty is high enough that you've gone from 'arrest on sight' to 'kill on sight' most likely. It can bug out though sometimes that even with a low bounty guards will attack on sight. Just run up to the guard and sheathe your weapon, and they should stop attacking and try to arrest you.

its not a glitch it is actually meant to be in the game if you look at one of the loading screens it says if your bounty is high enough then guards will not accept your yield and will attack you on sight

At some point someone saw you kill someone (being hidden and having a one hit kill is the most obvious way, but there are times when you wonder who the heck would of saw you) or it could be a group of reasons:
http://www.uesp.net/wiki/Skyrim:Bounty#Overview

If you exited out of dialogue with the guards and ran for it, they are still hunting you. The link I gave gives some examples when guards will look the other way, but if you have gotten that far in over your head past the point of dialogue im not sure what the option is other then using a console command on any holds in which you have a bounty.

The fact that you can be completely hidden and one shot kill someone, then have witnesses is crazy. If you do not see me kill someone, and not bounty goes up how do you know I killed the person? I have had this happen frequently where I will kill someone completely hidden from the shadows, kill a target in a hit, not have it say my bounty has increased - yet I have a bounty and guards attack me sometimes....

A dog saw me kill its master +1000 bounty then I killed the dog and lost the bounty. Its also no restricted to any one hold. I did kill that person that sent a contract out on me for stealing from them. While leaving the contract note on there corpse. Think the npcs are that smart?

its becuase you have a curved sword CURVED