When trading with a Custom Villager the arrow on the trade GUI appeared black instead of white.
Here is the Command used
/summon villager ~ ~1 ~ {VillagerData:{profession:nitwit,level:2,type:plains},CustomName:"\"Buggy\"",Offers:{Recipes:[{buy:{id:coal_ore,Count:1},buyB:{id:bat_spawn_egg,Count:1},sell:{id:coal_ore,Count:1},maxUses:9999999}]}}
Update:
It seems that the arrow changes color on what is wanted for when I changed the currancy to Gold Ore and Blaze Spawn Egg the Arrow Changed Yellow. I provided an image if what I found. 
Here is the code used that turned the arrow yellow
/summon villager ~ ~1 ~ {VillagerData:{profession:nitwit,level:2,type:plains},CustomName:"\"Buggy\"",Offers:{Recipes:[{buy:{id:gold_ore,Count:1},buyB:{id:blaze_spawn_egg,Count:1},sell:{id:diamond_ore,Count:1}}]}}
