Nah, toasty has a point. There is no definition to the textures. Like on the parking barriers, there is rust on the box section, but really if the metal had degraded then the corners would be more damaged than the rest of the surface. like this:
http://www.istockphoto.com/file_thumbview_approve/6897271/2/istockphoto_6897271-old-metal-box-isolated.jpg
ok, so rather than just criticising....
Try and lay out your UV so that you have connecting faces next to each other on the UV, and as much as possible avoid using the same UV space for 2 faces. This will make it much easir to paint rust damage on the texture when the rust needs to spread across 3 faces to create a degraded corner!
Also, with rust especially, instead of painting the rust over your texture (so that you get totally brown sections) try using overlays.Overlaying using multiply with a dark rust texture over the surface gives a nice damaged effect.
Hope that helps.
Peas out!
I want robotic legs.