I am sure you could...and I could have/will fix my texture later so that there are only spots of dirt on it. As for taking away the specularity and glossiness of materials in MR, just decrease the specularity, and increase the diffuse, even add a bump if you need to.

Check out this tutorial, it might help ya out.

https://www.digitalproducer.com/2003/...stex031125.htm