Out of curiosity, how do those red marks line up with the phaser hits from say, TWOK or TSFS?
..The hits on a completely different starship? One lost a decade before?
Not too well. We see a starboard side view of the ship here, and a top view with markings predominantly on the starboard side. But all the action in ST2 was with the port side of the model(s), and even the bridge "damage report" display in that movie showed precious little happening on the starboard flank of the saucer. There's something on the starboard side of the secondary hull there, though. If you squint a lot, and selectively ignore some things, you could pretend to see a correlation.
http://movies.trekcore.com/gallery/albums/twokhd/twokhd0469.jpg
ST3 shows such damage in "physical" form, compensating for the final ST2 scene where the damage was blatantly missing:
http://movies.trekcore.com/gallery/albums/tsfshd/tsfshd1069.jpg
The starboard nacelle tip damage and the forward secondary hull damage could be said to coarsely match Scotty's red marks. The aft secondary hull damage is much farther aft than the mark, though. And the match with the ST2 diagram is approximate at best, too. Funnily enough, the hits from Kruge's (stun/capture?) torpedoes seem to have left no mark!
Or, perhaps later in TUC itself, during the attack at the end?
Saucer portside damage isn't marked; marks for starboard damage don't match perfectly, but two of the crosses are sort of in the ballpark.
http://movies.trekcore.com/gallery/albums/tuchd/ch12/tuchd2299.jpg
http://movies.trekcore.com/gallery/albums/tuchd/ch12/tuchd2363.jpg
So Scotty is being about 50% prescient... The expected track record for yer regular charlatan, I guess.
Timo Saloniemi