This is what I do:
Since we live in a tropical country, most of us use electric fan for ventilation, many doesn't realize that air coming from the fan directly hits the eyes which irritate & cause to tear more. More tears = moist/wet whiskers, it is an ideal breeding ground for bacteria/fungus and they are the culprits for staining. Using air conditioner is not an option for me since most of the show venues here are not air conditioned, the problem with that is when the dog is used to cold temp, it will not perform well in an open air show sites, especially if the weather is hot. What I do is use a cooling pad from coleman, it's called blue ice, I freeze it, wrap it in a towel & put it on their beds, I even use it on the table when grooming. This cools the dog w/o irritating the eyes. (No electric fan needed)
Stains also come from food especially if you feed your dog w/ commercial dog food that has sugar beets & other colorant ingredients. You may control the staining by adding ACV (Bragg's - Apple Cider Vinegar) 1ml/100ml of water. Some dogs doesn't like to drink it, if that happens, you may add .3 or .5cc for about a week & increase w/ increments of .5 ml. until you reach the full dosage. Btw, I did this when my dogs are still in kibbles, all my dogs are raw fed now so I don't give ACV's anymore.
In grooming, I wash the whiskers twice a day.
Shampoo - #1 All Systems Pure White (undiluted)
Conditioner - Silk Creation Conditioner
Last Rinse - Boric Acid Solution
Boric Acid Solution:
Dissolve 1c hot distilled water + 1tbsp Boric Acid Powder
Let it cool then use it as last rinse
Keep the eyes clean by flushing eye solution every after bathing, grooming the face, etc. Clean eyes will not produce excessive tears. I use this as an eye flushing solution ---> http://www.medkaau.com/album/det ... f6828b097e60924bb1d