RCA and XLR shorting plugs??

I see Cardas as well as Acoustic Revive make shorting plugs for unused rca jacks, Acoustic Revive have them for XLR as well. Do any audiogon members use them and if so , what effect does it have?
The RCA Cardas are not shorting plugs. They simply cover the unused jack. They are a nice cosmetic addition that keeps dust out. I use them throughout multiple systems and have never noticed a sonic impact.

Music Direct sells a cheaper knock-off that is not as well made or as good looking, but still gets the "job" done.
I totally agree with Onhwy61. The Cardas plugs - which I also use extensively -- may produce a slight degree of quieting in my system, but that is no certainty. As for shorting plugs, best to check with the manufacturer(s) of your gear since not all components will respond well to their use.
They are great dust bunny stoppers for sure.
Actually, Cardas makes both the dust cover "caps" (which are described abvove) as well as genuine shorting plugs. You can buy both types frm Dedicated Audio (the shorting plugs are not actually listed on the website but they cary them). My Jeff Rowland Capri's manual specifically recommended using shorting plugs to avoid pops when switching sources.
Correct. An expense way to keep the dust out. Cardas has a video about the caps that is a gas. Reminds me of the three cup trick. Put the ball under one and move the cups around. Now, which one hides the ball? Dude!
As Dgaylin mentioned, Cardas does make real shorting caps and they do work. I was getting some cross talk from my VTL pre and put the shorting caps in my unused inputs & that solved the problem

The caps you usually see simply keep the jacks clean & they come in both RCA & XLR, as well as other configurations.

If you google "rca shorting caps" you'll find a lot of info, including DIY on the cheap. The only thing I would say is to make sure the manuf. says that it's ok to use on your gear.
Here are some cheap ones.LINK>>>[http://www.mcmelectronics.com/product/27-5335]
I use these analog terminators on my RCA jacks and the digital terminatiors on unused s/pdif jacks on my CD player. My wife gave them to me as a Christmas present. Was there a huge difference? No, but I though I could hear a small change for the better. They are not expensive, and are very well made for the price.

By the way, NEVER put them on an unused output jack, or you will kill the amp/preamp/player.