Many addons has one serious visual problem. Something what i'm calling "cushion" lighting. Models are missing sharp edges.
O2 doesn't have smoothgroups like (for example) 3DS MAX. It has just smooth (round) lighting for edge or sharp.
Again - it's not a smooth or sharp polygon, but smooth or sharp edge. It gives way more possibilities when creating model. I think best what i can do is show some exmple pics.
When you are modelling in O2, all created edges are lighted as "round". So modelled (or imported from 3DS) object looks like this one:
Wich is how most addons look.
But there is possibility add some sharp lighting at edges. Again, many model makers is it doing wrong. Selecting whole object and pressing "U" key with result like this:
But right way is select only edges (or faces) wich you want have sharp and result should be like this:
Good example of simple model is drink glass:
There is wireframe of it:
In Buldozer it looks like this:
There is clearly vissible how wrong it looks. There should be sharp edges at least at bottom and top of the glass. So first i selected only top points of it and give them sharp lighting and then bottom. Here's result:
Now it looks right.
Key for making edges sharp in O2 is "U", make them smooth you can with "I".
If you already know it, i'm sorry to annoy you with explanation. If not, i'm glad to help.
Good luck with edges!