Sometimes when I buy a new Metal Halide (MH) bulb, you can see little balls rolling around or the inner arc tube is hazy white. Is that normal or is that new bulb no good?

The little balls rolling around in the arc tube are metal, that is the “Metal” in the Metal Halide/MH. The white hazy is the gas in the Metal Halide/MH. Both of these are normal for a Metal Halide/MH, and yes the bulb is good. Bad things to look for in the bulb are: After using it a few times you notice “Black” spots on the inner arc tube, that would be a bad bulb that might need to be replaced. Letting a bulb run hot continuously causes the outer lens of the bulb to discolor which does not let light through. The power going out when the light was supposed to be on. The bulb Re-Firing when the bulb is still hot. These all will drastically shorten the life of the bulb, causing the inner arc tube to prematurely turn black which does not let the needed light spectrum through.