Amazon is putting a blue and black border around some of the CA on the site.
This raises a few issues.
These questions only arise when there is no other CA available that is clearly ID’ed for a specific release.
eg
About a year ago, I ordered a CD from Amazon that had that blue/black background.
What I (just recently) realized is that this was printed/created by Amazon! Just over the barcode on the back was the message “Manufactured by Amazon.com kydc, Lexington, KY”
Once I realized this, I ordered another copy of the CD with the proper album cover and produced in the place I expected! All I can figure is that some artists(?) choose to allow Amazon to print the CD for them on demand. On the inside is it marked as “Compact Disc Digital Audio CD-R Format” which makes me think these are not mass produced, but done on demand.
Yep. As you can see here, there’s also “CD-R Note: This product is manufactured on demand when ordered from Amazon.com.”
I guess now we know: That cover art is appropriate, but only if used for a release in MB which represents that specific Amazon on-demand CD-R.
You could crop out/ edit out the blue/black border, but I would be very cautious in doing so. I’m a bit OC about getting the exact same cover in MB, including logos, text placement and colour variations - and Amazon is notoriously bad at getting anything right at all.
In regards to scans that are cut off or tilted - I personally think anything is better than nothing, particularly if it helps identify a release (eg shows the back). If I’m really attached to a release I can edit a tilted picture, but it’s usually not worth it 
I can see this info fitting into “Annotation”. But that wouldn’t seem to form a separate release. (?)
Is there some field that would capture this well?
An on-demand CD-R (as opposed to a ‘traditional’ CD) with a different cover more than qualifies as a separate release in MB.
This is OK with me.
I will use “Tracklist/Medium/CD-R” to differentiate this release’s metadata from a traditional CD release?
Putting the new release as a CD-R* is a given, I would also add an annotation saying that it’s an on-demand CD-R from amazon, and probably a disambiguation too.
Too much information is always better than not enough.
That, + the different cover art, should make the release quite identifiable.
*since you’re adding releases that you don’t have in hand, be aware that you’ll always end up making mistakes.
We’re making a lot of assumptions (although informed ones) about these releases. An edit note making this clear is really helpful to future editors, for instance - “not in hand, information from amazon, please edit if you have a better source”. You might also have to leave some things blank, for instance the release date in this case (unless you can find out when Amazon started offering this service for this specific release)
Ideally we would have a release in hand when editing/ adding, and we want to err on the side of caution if we don’t 
As a follow up, I received a copy of the original release (non Amazon one) today. In my case, the DiscIds matched(!) and a did a bit compare on all the tracks and they matched as well, except for 5 samples on the last track.
So, at least for my release, the music is the same, but the Amazon produced one is lacking the graphics on the back and has no booklet.