It really depends...
As said above, some are just random trolls who do it really just to bug your eyes.
Then there's people who actually make their OCs and whatnot with 'unrealistic' colors, I don't know, maybe some are custom species so it's normal for them, but as long as they actually RP properly, I have nothing against them. Not, you know, I ma queEn of al elemenetes!11 uendrworl and haeven, ther4 I am OP11!1 pOSSesS E vERYTHING!111 and look like an unicorn! (I'm actually fine w powers lol, just not ones who abuse the living days out of them)
I don't know what to say about neons, though... I mean, as long as they don't make it so that your eyes rot away... (In that I mean neon body, neon markings, basically neon everything... Basically the trolls.) then it's fine, like markings, eyes, etc.