Thank you for your comments! I see that I can check the actual & effective dpi in the preflight panel but will have to investigate on how to change things in the preflight settings in the CS3 version. It sounds like that might be a solution if it can tell me that the scale percentage on an image is at 100%.

To answer your question – By scale (Images only) I will relate an example. Image A is 4″ x 5″in Photoshop. When I place it in Indesign and resize it to how I want it (let’s say to 1″ x 2″)… I then have to go to the original image (Photoshop) & change the size of it to 1″ x 2″. I then update the link in Indesign and check the scale percentage to ensure it is at 100%. (This is how I was taught).

This process is great for a few images but when there gets to be many it can be a challenge to ensure they all have been (double) checked. Sometimes I have copied all the background elements into Photoshop and create one image of them for ease but I thought it was worth asking whether there was a way to track them in a listed format in Indesign.
A script sounds like another great solution! Thanks!