I have had working dogs ferts etc etc all my life I have yet to pick any animial due to his/her eye colour or coat .
I like having white ferts for the same reason but I would never not enter a polecat because I might not see it .
Truth is if your working a set on your own that so big you cant keep a eye on the whole of the set then is best to move on to one you can
Each to there own but rather a good worker rather than a fert that I like the look off ]
ATB Cookie