Riki, I've never heard that this problem was related to colour of the cat. doubt that is a factor really.
As its been an ongoing issue for all his life,..I'm guessing Sunny is part Persian, and this is more likely where this stems from.
As you've noted, eye drainage is extremely common with this breed.
Though some dont have it, most do. How much varies from mild to severe.
My Persian cat has minimal eye running... just an occassional wipe is fine. The Himalayan need dailly eye cleaning.
It's not a health issue - providing there is no indication of green discharge present, indicating infection, or the eye itself doesnt appear red or sore looking. That would naturally require vet attention.
But for the rusty coloured discharge, which does look like dried blood.. regularly wiping the eye when needed with a warm wet cloth ( no soap) as you've been doing, is all that required.
That's all I've ever done as well, and after six years, neither has ever had an eye infection or any health issues related to this
If left unattended, over time it would get heavlily crusted,the eyes would become sore, infections would follow. Some persian cats whose care has been badly neglected can have absolutely terrible looking eyes, and severe facial staining.
I dont believe there's anything that can lessen or eliminate this tearing, unfortunately.
For the fur staining, which cant be avoided completely in light coloured cats,.. especially as they get older, I just use a face cloth with a bit of mild soap to cleanse,..carefully avoiding the eye of course. There's also several commercial products available, such as Eye Envy, which apparently work well.
When you judge another, you do not define them, you define yourself - Wayne Dyer