As a fan of a certain age...did I spoil myself rotten.
As LIfeGaveMeLemons mentioned, one of the very first sites I encountered when searching for Sailor Moon was Hitoshi Doi's Sailor Moon fan page. Since I only knew the DiC dub at the time, it took me a moment to get the names of the characters. In fact, I was surprised there was more Sailor Moon after the first 65 episodes stopped airing, since I thought the series ended on that note and was just cancelled. To me that there were more Sailor Scouts for all the planets was a shock in of itself (I had some very, very vague ideas of what a Sailors Neptune, Pluto, Uranus, and Saturn would be like but I largely assumed they just didn't exist). Strangely, I wasn't surprised by Chibi-Moon, because I thought she was going to become a Sailor Scout, but her color scheme actually endeared me to her much more to the point where she remains my second-favorite Guardian to this day.
Also, even though Hitoshi Doi did have episode summaries, between the difference in the names and the fact that the summaries were text, I didn't read all of them or understand what was going on. I was open to the idea that there was more Sailor Moon material out there but I had no idea what was in it. I actually thought for a time Rini had an older sister from the Negamoon.
Then there was Ken Arromdee's Sailor Moon FAQ which cleared up a lot of the confusion I had. I liked that it also clearly delineated between the dub and the dub so I knew who was who.
But the real gateway for me to understanding it all back then was Castle In the Sky.
By the time I got to Castle in the Sky, I had learned some things prior to that page, but that page really dedicated itself to noting the difference between the dub the original version. By then, my inner fan had been roused enough to ask myself questions such as "Why didn't any of the Sailor Scouts get affected by the negative energy?" Then answer to that came in the form of the illustrated episode summaries.
By looking at the summaries I could see what was unfolding, and that the author used dub names helped me tremendously. I didn't quite get what was going on with Esmeraude and those dark henges although I gathered it was similar to what Rubeus and the Four Sisters were doing. I remember thinking upon reading the summary of Serena and Darien's reunion, "What would have happened if Rini hadn't had that bracelet removed from her, and why is she always saved in the nick of time?"
Then the episodes showed the Scouts going to the future (at last), then Rini being converted into Black Lady (My thoughts were, "You mean that WASN'T her SISTER? That was HER?"), and the rapid decimation of the Black Moon Clan. I eagerly awaited the S video summaries and read them...only for them to be voluntarily taken down once the episodes started airing on TV. I still looked for everything Sailor Moon related on other sites, most of which I have sadly forgotten. Back then I wished there was some centralized location to find out this information, but looking back on it, I was foolish. There was a fun to the scavenger hunt-era of fandom that just is not possible now, since everyone knows everything.
And if I am honest with myself, reading all of those spoilers and fan sites did affect me and my views of Sailor Moon in a negative way.
Before I had access to the Internet, Sailor Moon was a TV show that aired, had its run, and like many cartoons, stopped airing. I didn't know what the driving force was to create new episodes. I just thought Sailor Moon was one of those shows that just ended.
Sailor Moon introduced me to the greater concept of fandom. Prior to that, I only knew fandom as Trekkies and while I liked Star Trek, I never felt myself be the level of a Trekkie, someone who would go to a convention dressed like a character and would know all the episodes by heart. Aside from comic book fans and Star Wars fans, I didn't think fans congregated together for anything else. I thought I was genuinely the only one who liked Sailor Moon as much as I did.
So when I connected to the Internet, at first I was thrilled. I would spend all night long in the summers to just meet like-minded people and to learn. That started spurring more concrete fan ideas than the ones I came in the series with or even ones that I came up with from reading fansites and fanfics. Seeing others like me encouraged me to latch onto the series even more and I wanted to know everything about Sailor Moon that I could. Unfortunately, that had two horrendous effects.
One is that I became a know-it-all, a canon purist, and led me to reject the dub entirely because it was too childish and I was too old to be watching cartoons. I wanted the original version, unfiltered, adult jokes and all. This was partially remedied by me actually seeing the original version and realizing I liked the dub more than the original version, but I was (and still am, at times) still a know-it-all.
The other effect is that when the new episodes were dubbed....I couldn't quite enjoy them as much.
You see, when Sailor Moon healed Catsy, Bertie, Prizma, and Avery in different episodes, it was a mild, but pleasant surprise. To be fair, I saw the episodes out of order, and thus I saw some of these episodes before the Rainbow Crystal and later Negaverse episodes, so I didn't know healing bad guys was Sailor Moon's thing. I thought she used her tiara or waved a scepter. I didn't know she could cure or heal the bad guys. The point remains that it was unusual to see her make bad guys good. Of course, I also wondered if the reverse couldn't be done, and then I saw with Darien that it was.
However, when I watched the later episodes that were dubbed, I could only compare them to the episodes that came before, how the entire tone of the show seemed to be different, and I was wondering how the episodes were going to be adapted. In addition, all of the moment I had seen unfold in summary format...seemed horribly underwhelming when watching them. I couldn't enjoy Sailor Moon for being that, Sailor Moon. Everything existed as a comparison to something else.
So learning about Sailor Moon has made me warier of spoilers in general, to the point where I try to avoid heavy spoilers in media where I can. Even if the journey is predictable, there is nothing like seeing it unfold with fresh eyes. I can't do that with Sailor Moon.