I underwent this transit a few years ago over mine too, and it was a very tumultuous period of my life- I wont give away the nature of the undermining "hazy" effect but it definitely did match with my chart ruler planet.
I'm quite young in SS, but how it appeared to affect me was exactly how Lydia described, but being naturally/natally an obsessive and intuitive mind, I was able to sort of see through the haze of my day to day mindless routines (occasionally, then throwing the thought of acting on said intuition off with a weakness unlike how I am usually) which had overtook the meditation focused routines I had been developing prior. I dont know the nature of how the transit will manifest in the scorpion 3rd decan of pisces- but I will say that over mine it forced out some 12th house stuff full on and my sudden lack of meditation and weakness in acting for my own favour led to emotional depression and typical Piscean 'nonexistence feelings' I would just lie around in bed all day quite often, and feel incredibly repressed (I luckily have a lot of Sun energy and vitality which helped pull me through- but I regret not being able to push that Will into meditation at the time *it was confusing somehow ??*)
When the transit occurred, a significant break happened in my life as could be expected from the 1st house/chart ruler- which Neptune manifested in many ways but notably through (at the time) my curiosity and ingestion of LSD, I had a complete ego break and lost all sense of self. It was not a positive experience at all (I had been achieving this naturally through meditation and instantly HATED the trip and wanted out- I had no control over my immediate environment for the duration of it) I am lucky the person I was with was someone I trusted, I could have been subtly scarred for life. I was somehow still loyal to SS through my inner convictions- but my relation to the world was disgusting. My mind would take the ideas and notions I would read about and adopt them fully in a way where I adorned them over my sense of self and identity with very little control or discrimination between one thought and the next.
I came into contact with aspects of my own power but also of my own weaknesses and things that I hadn't yet accounted for through work- able to see every detail (virgo) of my issues and setbacks in life just like I could also see every detail of the music and ideas I lost myself in in an enforced escapism. It would have helped to have a better understanding of those virgo energies of detail, but I was still too young and naive at the time and it was hard to make sense and civilisation out of any of it.
It is definitely a malefic transit for most people, but our people can deal with it easily and learn much about the universe and ourselves from it's fucked up "inspiration", I am lucky of my own natal inheritance and mind that I could manage and not fall into deep confusion and dread.
I will write more on it if there is interest as I sort of rambled about my person a bit.
The important counter to this transit, and understanding things through it is an organised and concise Mind (virgo) with a Plutonian focus but it is quite hard especially if your routines are poorly kept or young like mine were.