Do Silver Cables Hurt Bass?

No, not if they're thick enough and your pocket is deep enough.

Have to back up what everyone has offered up. I think wire gauge is one of the more important factors in bass reproduction(assuming the speakers can reproduce those frequencies). Lower frequencies are produced by woofers(duhh), which have larger cone area(also duhh), this requires increased current, compared to mids/tweeters. Current delivery is aided by larger conductor size. Some silver might get a bad rap, as you said, because wire guage is often much smaller.

I also have recently upgraded to silver interconnects and have found the bass to have tightened up a lot. Much better definition though, in parallel lead and bass runs on much of Jethro Tulls work the tandem melody lines are enhanced without the boominess as an example

Does anyone have experience with Kimber KCAG, they are silver?

Kimber KCAG is as Nedlabs_stereo says. Better for tube amps and/or soft dome tweeters. KCTG is same, but 2X the conductors, better bass. If you are at all interested in KCAG, do yourself a favor, and check out HomeGrown Audio. They have the same cable as KCAG, except theirs is solid core(5 - 9's 22 ga. silver, teflon insulated) vs. stranded. I find it superior(but very close). A little smoother, more liquid, less veiled. But, you'll REALLY love the price: $70(RCA terminated)/m!!! If you're willing to put the cable together yourself, price would be about half of that! How do they make money? THIS is what wire should cost.