I expect them to be clean. Other than that I don't have any expectations. I happen to like bright colors so I think they look nice. But nails (like many other body parts) are not something I really notice or pay attention to unless there is something really wrong with them. Kinda like eye brows, I've said before that I don't care about eye brows at all and girls who worry about them are really worrying about the wrong thing.
Well I was kinda wrong, partially. See there have been times where I've noticed someone (ok a girl because I don't care if a guy's look bad) and thought that they really need to trim their eyebrows. That being said, I've never noticed a girl and thought "she has really nice eyebrows." Not because my eyebrow standards are high, but because it's more of a maintenance thing. If they look alright, that's all that's required.
Back to nails, it's kinda the same thing. Nails thanks to polish and coloring you get a little more play with them, but they're still not something that are going to catch my eye. Beautifully designed with 10 layers of polish, or just clean and plain, both work. Thankfully in my experience they aren't something that girls worry about (short of breaking one) and are treated more as an art project.
I can't stand a bunch of goop and long nails because I want an active woman who can sail and ride a bike and operate things, tie knots, and so forth. All that cosmetics and make-up -- I threw away a 50 gallon barrel full after one woman left it under the sink over time. No make up, no nail jobs, no little jewels or pretty designs on the nails, frenched or whatever. Way too finicky. Gives me the creeps.