As far as I know, the problem people have with them is when someone has a story that's like "Simba meets a nearby pride of pink lions!" At least as far as sparkle TLK OCs goes. There are some people who just find the colors to be too bright and painful to look at. Others are just against people doing recolors of screenshots/some else's art and most recolor "artists" like to use unnatural colors, or so I'm told. Personally, I don't mind them at all if they aren't inserted into the TLK universe (or another universe with nonsparkle characters), but if someone wants to do that, they are allowed to, so even when it does happen I don't go hound the people about it or anything. Some people just take this stuff too seriously.
Yeah, I don't mind unnaturally coloured-characters, as long as they aren't recolours of someone else's artwork. It's not my place to judge someone's OC, especially since one of mine has red fur. xD Granted, reddish brown, but still red.
I've always felt the same way. I mean if someone has an OC you really don't like, all you have to do is not look at it/read about it/RP with it and problem solved. No reason to give them grief about it.
