I had some older NiMH AA's that I ran through three conditioning cycles (all "soft" recharge) on my Maha MH-C808M. After the third cycle, I left them sitting for at least an hour before checking them with my ZTS MBT-1 tester. They weren't hot or even warm before testing, even when fresh out of the charger. All of them showed 100% on the MBT-1.
I had four of them in my left hand, getting ready to put them into the battery holder of the device in which I use them, and suddenly felt a burning sensation on my ring finger.
I let go of them in a hurry. I don't see any blistering or even a red mark, but this isn't the first time I've run across this.
Before I had the pulse load testers, I'd check batteries with a cheapie digital voltmeter. At least once while holding the DVM probes onto the respective terminals on a battery, I've noticed some uncomfortable heat from the positive probe. Again, not enough to cause injury, but enough to make me let go of it quickly and say "ouch," or words to that effect.
Is this something wrong with those batteries, or do I just need to change my battery testing techniques? I don't think the positive terminal on the battery or the DVM probes made contact with my wedding band, but I s'pose that could have happened. Unless both terminals had somehow been connected, though, I can't see how any kind of short circuit occurred. My hands weren't wet, and I don't think I'm that good a conductor.