I use it a lot, the thing to remember is the answers (tiny muscle movements that make it swing) are coming from somewhere, probably somewhere inside your own body-mind/soul/spirit etc, BUT the big question is, where?
For example, the answers could be coming from your desire to prove it wrong (not saying that was what happened in your example Orismen, but could’ve been) or in another case, from the user’s more deeply buried wishful thinking/denial mechanisms - the part we all have that makes the morbidly obese guy with the heart bypass think another triple cheeseburger can’t do him THAT much harm, to give you an example of a layer we all have to some extent (no magick needed) that can fuck us up when it comes to decision making.
In other words, it could just be telling you what you wish on some level to hear the most.
Getting that crap out the way has been the work of years for me, and I don’t think I’m especially all that screwed up to begin with, so those are all things to factor in when using this.
You COULD consecrate your pendulum (and therefore the entire act and intention of using it) to your HGA/higher self/whatever, to give you the answers that are in your own best interest - and if you use it much, you’ll start knowing when a pendulum reading is giving “meh”-type answers, or just idly swinging and not going in any one direction, or you could consider consecrating it to another being e.g., Thoth, to grant you knowledge.
I’m interested in it as a tool because 1. you can carry it anywhere, I used to use a bracelet with a charm at one end I wore all the time, and 2. because the answers are mediated by my own muscles to be shown in the pendulum, I figure it might be a good way to internalise divination, and I have in fact got accurate results just “imagining” what it would do, or holding my hand out and “feeling” where it would swing a pendulum.
IMO it’s an underrated tool, but then again it doesn’t have the depth of meaning carried by tarot or runes, so I can see why it’s not always highly regarded compared to those.