having built a few cables in my day, I would advise against it. They do seem of decent quality and often do have a rubber seal, however, I do not believe that isolates all openings of the connector, such as the set screws and such.
Maybe water resistant, but I would not consider them waterproof
Primary #1+Auxiliary: Burning River Pale Ale clone
Primary #2: empty
Primary #3: EdWorts Apfelwein #4
Conditioning/Drinking:Brewers Best Belgian Tripel, Apfelwein #3, EdWorts Apfelwein #2, Cranapple Wine, Routers Share Network Closet Strong Scotch Ale, McCormack's Old Malt Oatmeal Stout