For generation one and two--I didn't look up any information at all, as I was too young back then and parents didn't allow me to use computer much. Only time I was allowed is when homework required me, and aside from that, I was also given a couple of hours every weekend to play some game--nothing else. Third gen games--I did try searching for some things, but that was after I'd gotten a hold of them and not prior, so it doesn't exactly count. Thing I was searching for was some guide to encountering those Regi. It worked, but took me a while. A decent while.
As for fourth generation, I haven't looked up any news or spoilers on it at all, and tried avoiding them as much as I possibly could. Did run into a thing or two accidentally, but those weren't too extraordinary; didn't ruin much things for me. When playing, I've had a lot of fun, and felt like as if I were experiencing something completely new, just as they wanted most fans to. For gens five and six, I wasn't able to dodge anything, sadly (I was extremely involved, rather), but still had fun playing.
Avoiding things like this could be pretty tough for me, but I still try every once in a while.