Totally normal. One of my dogs always had the funny coloured discharge it never bothered him and I never cleaned it

he lived a long and happy life.
Neither of my dogs now have it, 1 cleans himself quite regularly and the other stretches on his stomach, clambers onto laps and never cleans himself but has a spotlessly clean willy. Probably because its constantly wiped on laps, furniture and carpets it doesn't have time to build up.