I think of octopus personalities a lot like the descriptions of cat's or young children's personalities, if you say they will do something as a response to some stimulation, they will fail to show that behavior soon after the statement (or conversely, if you say they don't do something, they will). I try to find a few, more or less common traits but never seem to be able to make a chart of something meaningful so a lot is anecdotal or remembered but not well documented. I remember Jean Boal comparing trying to study octopus behavior and switching to cuttlefish in a NOVA interview. It took a bit to find it but her quote well points out my point. The article is worth a read but here is the quote I was trying to locate:
In terms of their performance in experiments, octopuses are unbelievably erratic. One day they will be brilliant and for the next five days they'll act like they don't know anything at all. So it actually takes pretty intense statistics to figure out what they know and don't know. In the past, I've had more consistent performances from cuttlefish, although sometimes they like to be erratic, too. In general I've had an easier time interpreting their performances, and they are more consistent than octopuses are.