so im doing a legion playthrough being as evil as i can be, mister sandmanning it up at every oppurtunity, using a super laser on an NCR base and being evil at EVERY oppurtunity, i even butchered goodsprings for the powder gangers yet my kharma is always at either good - very good.
is my only option to steal every item i see even the useless stuff i.e pencils etc...i just cant seem to bring my kharma down at all

Maybe a glitch, or you just did something very good. Sometimes killing a guy before you figure out that they're evil or something can give you karma. Happened to me in Nipton, with the guy that won 2nd place in the lottery. I killed him and gained karma from it

Well for some stupid reason Obisidian decided that killing Feral Ghouls, Powder Gangers, and Fiends would award you with positive karma; that's probably the reason you still have good karma. Although the karma gain for killing Feral Ghouls has been really spotty for me, so even that might be a glitch. >.>

If you're on PC try this mod: http://modsreloaded.com/bad-karma

The mod description also explains exactly what the numbers are for karma so you'll understand why it is so messed up to begin with. If you can run the mod, if you're doing bad things it won't be long before you reach evil status.

I'd suggest just ignoring karma in general, there very few instances where it will affect the game. If you want to do an "evil" playthrough then just do things that you think only a true pure bastard would do.

Note: The Legion aren't evil. They are the darkest of the grey factions of New Vegas, but they aren't generic black hats.