Hey, Kai! Long time no see.
I like to think that I play them a lot differently, or I would, if I got the chance. But then again, you can do that with ALL the core races, instead of just playing them as funny humans (The best example I saw was an elf who was very casual, very slow with things; he'd just go romp off on a side trek because he HAD Time; an elf who commented about how ridgid and unfriendly human castles are, requested sleeping in trees over Inns, etc).
However, I would agree that a lot of people play them like humans. Because well... we're humans. What else do we have to go on? It just takes some looking outside the box, I guess, and getting into the character's skin: the best way to think of it, is to Think Like the Race. How do they act? How would they see the world? Would an Orc see things the same way as an elf? Look at their culture, and reflect on that. I myself played a Kobold once who was too... 'humanish'? I'd love to give it a shot again. But I've played different races (in non-combat games; roleplaying online, whatever) and I think that sometimes, I've done a lot better.
Let's take the example of a Kobold. A kobold is seen as Cannon fodder by anything that can swing a stick. A kobold is short, weak, and looked down upon.
Kobolds are going to have an attitude. A chip on their shoulder. The world is out to get them, so they better take as many out as they can, while they can, and keep on livin'. They are going to be vicious when they have the upper hand. They are going to be sneaky, and plan, always have a Backup plan, a plan C, an excape attempt (or two), and they are never going to get toe to toe (Unless that's the Kobold's schtic). They are going to be cautious. A kobold can be a McGyver. That inherit +2 to trapmaking can mean a lot. They can think of ways to hinder individuals, while staying out of the line of fire. A 30ft speed and a +2 to dex means Hit and Run tactics are a natural skill.
However, within this framework, a Kobold has a lot of potential. They can be outwardly snippy and vile towards others, or they can play up their race's apparent 'ineptness', and act like a snivelling coward. They can play up the unexpected overlooking of 'It's just a kobold'.. Until they drive the knife into your gut for +6d6 of Sneak attack damage. They can be wheelers, dealers, and so on.
While they also can be survivalists, and out for Number One, can also understand the idea of Strenght in numbers, and use Teamwork to their best advantage. These people can save your life, or they can get you killed. So you either need to get out at the first sign of trouble if you can't trust them, or help them as much as possible, and get out of you don't get the same.
Or, they could actually be good. While keeping the Kobold Tenants (A Kobold in Melee is a Dead kobold, always have a backup plan or three, prepare), they can be good. They are said to be the decendants of Dragons, so they may uphold themselves to the glory that a Dragon ideals, such as a Gold or Silver (I'm thinking Kobold Paladin here).
They could want to show the world a Kobold isn't a weakling. They could revel in the power, but never lose sight that they are still killable. Maybe use intimidation, bluff, and so on.
Now, I could do another race, if you like? I hope I answered your question in this longwindedness...