a lot of skins have this function
most people are used to vlad being red
when he's using soul stealer skin, he has a tiny, but noticable advantage in prolonged encounters where most people are not used to a green guy doing vlad things because it breaks the psychological imprint they have on him
Then there are counter examples like snow singed. His vanilla skin emits green poison which kind of blends in the background and may cause people to take extra damage than they normally would, but snow singed has white particles that clearly stand out and warn people away from his trail of poison