smoker..repaint or leave it

You probably have a couple options. You could repaint it with high heat paint. Or give your firebox a lite coat of cooking oil and then fire it up and let it season.

I assume you are talking about the exterior.  

IMHO If you have rust, you need to do a really good sanding to stop the rust.  Then paint it with a high temp paint,  There are 3 different paints on the market.  High Temp paint, Header/exhaust paint, and Wood Stove paint.  I learned the hard way that you should use either header paint or wood stove paint they are made for the higher  temps that your firebox will give off.  

I recommend doing multiple coats and lightly sanding in between coats.  Put it out in the sun for a couple days to bake the paint in before firing up and I would let the paint cure for at least 7 days.   

If you know someone who can sand blast it, that would be your best bet for prep.

Good luck!

Smoke ON!

- Jason