"Does God like nail polish?"
This was the question my daughter asked me recently. My answer came quickly and somewhat abruptly.
"No."
Upon further thought and prayer, however, I would now like to change my answer ... slightly.
Does God like nail polish?
Well, that depends on your motivation for wearing it.
The Bible doesn't specify whether makeup is good or bad, nor whether God is in favor of it. It's mentioned three times:

2Kings 9:30
When Jehu came to Jezreel, Jezebel heard of it, and she painted her eyes and adorned her head and looked out the window.
Jeremiah 4:30
And you, O desolate one, what will you do? Although you dress in scarlet, Although you decorate yourself with ornaments of gold, Although you enlarge your eyes with paint, In vain you make yourself beautiful. Your lovers despise you; They seek your life.
Ezekiel 23:40
Furthermore, they have even sent for men who come from afar, to whom a messenger was sent; and lo, they came–for whom you bathed, painted your eyes and decorated yourselves with ornaments.
While each of these verses address the use of eye makeup, I believe nail polish fall squarely into the category of painting your body, and as you can see, the God does not speak against it, but merely mentions it.
They grey area for me is in the motivation.
Why do you want to paint your nails? For that matter, why do you wear foundation? Eye liner and shadow? Colored lipstick? (Chapstick is protective and often necessary - NOT talking about that.) There are three likely reasons.
- It's a creative outlet. It's fun to change the color of something, or to paint a little flower on your fingernail. If this is your motivation, I say go for it. Everyone needs an outlet for creativity. No problem.
- It's a way to get attention. This is where sin starts to creep in. Makeup is often used as a way to make oneself more sexually attractive. The Bible clearly states that beauty should come from within. (3)Do not let your adorning be external—the braiding of hair and the putting on of gold jewelry, or the clothing you wear, (4)but let your adorning be the hidden person of the heart with the imperishable beauty of a gentle and quiet spirit, which in God's sight is very precious. (1 Peter 3:3-4)
- It's a way to correct flaws. This is by far the biggest problem with makeup, as I see it. Many girls have a poor self-image and they try to compensate by painting themselves to "look pretty." The Lord God personally crafted each of us. By correcting "flaws" with makeup, many girls are in essence saying, "what God made isn't good enough." They feel the need somehow to improve on what the Creator Himself created. How sad.
As husbands and fathers (or potential fathers) we need to make sure the young ladies in our lives know they are beautiful just the way they are, and that no amount of stuff they cake onto themselves will improve on what God intended them to be. We have to reassure them that they are wonderful and that makeup, while it's fun, is not an upgrade.
Conclusion:
In my humble opinion, makeup is okay if the goal aim is to have fun. It becomes a problem, however, when you avoid going anywhere until your face, hair, nails, etc. are "perfect."