Some of my solutions:
(http://img34.exs.cx/img34/5311/DSCN0043.jpg)
The one on the left (my own idea) is a six-inch length of plasic tubing, obtaiable just about anywhere where fish-pong accesories are sold. It is simply split for an appropriate length and slid over the male QC till it reaches the female. it slides out of the way whilst connectios are being made, then over both QC's. It stays in place well enough to protect carpets and laminate flooring, but I would not trust it to stay in place whilst being dragged over upholstery. This piece of hose has been in use for several years, cost = a few pence.
The next two are commercially available. The middle one was the cheaper of the two and features a small rubber sleve. the last is the most effective as the brass is almost completely sheathed in hard plasic. It is also the most expensive I got this one from Ashbys, but I am sure they must be available elsewhere.
I am sure that John would agree that they are sometimes worth a great deal.