Why does Quark have so much purple around his eyes? Is that natural pigmentation, or does he wear eyeshadow? I can't think of any other ferengi (except maybe his mom, kinda) in star trek history having this trait. Sure maybe ferengi males customarily wear make up or something, but we've never seen that before (to my recollection), so it's likely just natural. I'm sure the reason is that he is supposed to be the shady character of the show, so the creators wanted to give him a typical shady criminal trait... But still, it's so weird that he's the only ferengi ever with this trait. Ishka has it too, to a lesser extent. She IS quark's mother... but is it make-up or is it in the genes? I don't think the other ferengi women we see have it. Any in-universe explanations? This is clearly a very pressing issue and MUST be explained thoroughly.
From a production POV, they did it because they wanted his eyes to stand out more. In later seasons, you can see Rom has it too, but not to the same degree as Quark.
I noticed when they introduced the Grand Nagus, sometimes he had the eye make-up, sometimes it was less prominent. Could be a difference in lighting between the scenes I suppose. I'm glad they put the eye make-up on Quark because it does distinguish him more from other Ferengi. I remember in the first episode, it was hard to tell him apart from the others.
If wearing eye makeup is something Ferengi do if they feel like it, as with humans, then it would definitely appeal to Quark. He loves his finery.
And what we think of as natural Ferengi nails might just be them wearing nail polish too. I can't think of any reason Quark wouldn't or shouldn't wear eyeshadow. He's a real fancy-boy.