Funny coincidence, I just put on a bean soup an hour ago, with beans I started soaking at noon yesterday. I meant to start cooking them around noon today, but went back to bed after waking up early and time got away from me. The pot of beans was quite foamy after soaking for over 30 hours, plus the room is really warm, probably about 75F. So, I thought maybe they started fermenting? Maybe they smelled a little like they were? I wasn’t about to waste them, though, and just rinsed them about three times, any questionable scent disappeared and they just smelled like normal rinsed beans. I added new water and put them back on the stove with a lamb leg bone and a duck neck. Smells good so far, anyway.
I thought I heard somewhere you can do a long soak refrigerated, if needed, or just changing the water periodically as already mentioned would probably be OK, too. I think they’re probably pretty hard to really mess up. I think I would just stick them in the fridge.