Top results are very hard unless the keyword phrase is not used much, but being in the results is not too hard. I have about 1,200 parked domains at the parking service TrafficZ.com. Most domains suck at getting type-in traffic, but many all get SEO traffic from people search for odd things at Google and Yahoo. I do have a few that are right near the top of the reults or at the top and they do pretty good. Of course I have optmized them well with 10 years experience behind me...
It may depend on the parking service you use, but for the most part I don't see any sign that parked domains are evaluated differently any other kind of site. They just have a big disadvange from normal sites because you are limted to how much content you can add, and most parking services don't let you do ANYTHING to promote them or get links.
But parking at Noomle is not really "domain parking". When you put a domain there you really get what I would call a mini-site. And if you add enough content I would drop the word "mini". Really, they offer a pretty nice templated content management system that works well for for those that have domains that don't convert at regular domain parking, or if you should happen to get some domains that are "banned" for some reason. I have over 200 domains at TrafficZ that Yahoo decided they didn't like and they got banned. TarfficZ does use 3rd tier providers, but they don't may much if anything. I moved 3 of my domains that were getting traffic to Noomle, spent a little time adding content and some optimization and the first month those domains earned about $7 with AdSense.
So I got $7 for 3 domains that were earning me nothing at TrafficZ (Which I love), so I'm happy and will be moving more of the banned domains there as I have time. But if I have domains at TrafficZ that make money, I won't move them since I don't have the time. I might try one just to see how much more I can make, but we'll see.