This is completely preference! By18-months they don't suck on their hands as much as they do when they are littler. I have a 7-month-old and I can't paint her fingernails yet because everything is in the mouth, but I paint her toenails. But that is more of a health issue.
If you are talking about whether it's ok paint her nails because it's wrong or it's like wearing makeup, that is totally up to you and if you don't have a problem with it then ignore them. You decide within your beliefs when she can wear nail polish, or lipstick or get her ears pierced! That is your decision!



