Holster Cleaning Question

[Mauser720]

I have a lugar artillery holster that appears to be original; however, I have not found any markings on it. It is very dirty. The main flap that goes across the top has been replaced, and the shoulder strap is a replacement. I would like to know (1) Do collectors generally frown on a holster that has been cleaned?; (2) If it is all right to clean it, is there a recommended procedure?; and, (3) Are there any cleaning and/or waxing or leather treatment supplies that are recommended for such a holster?

Thanks in advance to anyone who knows something about this and can share some information with me.

Ron