Though I have never tested the idea of over-pressure, in .38 Special, or any other pistol cartridge, I have often wondered how over-pressure would be detectable in a (relatively) low-pressure cartridge. I know what to look for. I've seen signs of over-pressure in rifle cartridges. I just can't ever remember seeing the signs in any pistol cartridge. When I work up a load, I always look for the signs. Mostly out of habit, I think. Just have never seen 'em.
One anecdote, here. At one time, I had a Colt Trooper Mk III. They were notorious for having "tight" cylinders. One day, I was shooting some light HBWC target loads. Even with that light load the spent cases were difficult to get out, sometimes. I occasionally had to tap on the eject rod to get the cases out. Some guy saw me doing that, and he moved a couple tables further over. Guess he thought that tight cases meant hot load.