I'm tired of seeing terrible casting suggestions just because they happen to look right, and then get downvoted to hell because I cast a brunette (who I believe could play the character very well) just because they are not blonde "like the character should be" (because hair dye doesn't exist apparently).

Also, as a rule I actually never choose actors whose work I have never seen. If I come across one that seems perfect that I haven't seen I look up clips of them on Youtube before choosing them.