How are phono cables different (related to hum issue)?

@scott_w  I should add a "YMMV" disclaimer.  Those observations are in my system, with my ears, and my listening preferences.  I've tried a lot of different cables and generally don't notice huge differences (if any) between better quality cables, but I do notice that when using entry level cables, they can make things sound worse than they could.

The Blue Jeans cables are a good value, but they can rob the music of some of its life.  They are a good option for turntable use because of their low capacitance.  Depending on the level of your turntable and system, you may find them a little "soft" and lacking some high end detail.  I've noticed that even more with their speaker cables.  For things where cables matter less, like a subwoofer, they are more than good enough.  I can't detect any noticeable difference between their digital coaxial cables and more expensive ones.  Their interconnects are OK, but you should notice better sound quality with better quality cables.

As others have mentioned, there could be an issue with the cable itself.  I had some very expensive Kimber Cables that I purchased second hand based on positive experience with some of their similar interconnects.  They were a fail with my turntable (bad hum).  I returned them and was told they were fine, other than a loose screw that held the shielding in place.  I replaced them with some Kimber Kable TAK-Cu cables (which were about 1/3 the price) and now everything sounds great with no hum.