It's pretty easy to tell if excessive DNR has been applied to a BD release. I'm pretty sure that we all all aware of the fact that human skin has pores and, in most cases, blemishes. Humans also have facial hair (eyelashes, eybrows, etc).
When you see a closeup, do you see these details or does the face look waxy with no detail in the eyebrows or individual strands of hair? You should be able to see the individual eyebrow hairs, for example.
The other criteria is that there should be a grain structure to the image. The grain might be fine as in "2001" or "Grand Prix", it might be coarser as in Clockwork Orange or "Dirty Dozen". It may increase dramatically during effects or process shots such as fades or rear projection or titles. The grain may increase dramatically in darker scenes and diminish in brightly lit outdoor scenes. This is the nature of film and it is the way the film looked in the theater and is no way indicative of a bad transfer.
If a title fails all these tests and did not originate on video, you can be pretty sure that you are seeing the results of excessive DNR.
Now comes the tricky part: Was that DNR applied during the creation of the DI (digital intermediate) in which case the film prints are going to have the same issues (not likely, at least not to the level we see in "Patton" and "The Longest Day" or was it applied somewhere in the video transfer and mastering process?
In the case of older films, there was no DI because the process didn't exist back then. So for films like "Patton" and the "The Longest Day", it must have been applied in the video transfer / mastering process.
Some films have been shot with filters on the camera to produce a soft, hazy, or dreamy effect. This should not be confused with DNR. The key here is a soft looking image without a lot of detail THAT STILL CONTAINS A VISIBLE GRAIN STRUCTURE. A prime example of this would be "Butch Cassidy and the Sundance Kid".
I hope this will help the more non-technical out there to understand how to evaluate an HD release for excessive DNR.